The Secret to Feeling Full on Fewer Calories with Barbara Rolls

James Hill:

Welcome to Weight Loss And, where we delve into the world of weight loss. I'm Jim Hill.

Holly Wyatt:

And I'm Holly Wyatt. We're both dedicated to helping you lose weight, keep it off, and live your best life while you're doing it.

James Hill:

Indeed, we now realize successful weight loss combines the science and art of medicine, knowing what to do and why you will do it.

Holly Wyatt:

Yes, the “And” allows us to talk about all the other stuff that makes your journey so much bigger, better, and exciting.

James Hill:

Ready for the “And” factor?

Holly Wyatt:

Let's dive in.

James Hill:

Here we go.

Holly Wyatt:

If you've ever tried to lose weight and found yourself constantly hungry, that's me. Or maybe you're cutting your portions only to end up eating extra portions snacking later. You're not alone. What if feeling full and satisfied didn't mean eating less but maybe eating differently? This isn't going to be an episode about not trying harder, but maybe working smarter. Today we're talking about one of the most practical and powerful strategies in the weight loss toolkit, energy density. It's the science of how many calories are in each bite of food and how you can use volume, water content, fiber, and even food texture to feel full while managing your weight.

James Hill:

Holly, this is one of those concepts that sounds simple, but believe me, it's not. And it has very important implications. There's a lot of evidence that suggests that people may tend to eat a constant weight of food every day. That's not a constant amount of calories because different kinds of food have different calories. If you lower the energy density in what you're eating, you can eat more food, more volume of food, fewer calories, feel satisfied, and stay in a calorie range that supports your goals in losing weight or keeping it off.

Holly Wyatt:

And whether you're just starting out, trying to maintain your weight loss, or navigating reduced appetite on these new GLP-1 medication, I think this conversation matters. Because learning how to work with your hunger instead of fighting it can be a game changer.

James Hill:

And Holly, we have the perfect guest on this episode to sort all this out. Dr. Barbara Rolls is professor and the Helen A. Guthrie Chair in Nutritional Sciences at Penn State. She is literally one of the world's leading experts on satiety, eating behavior, and weight management. Many of you may recognize her name because she wrote the book, Volumetrics, that really shows you in detail how to use energy density to lose weight. And Volumetrics is always rated as one of the top diets out there. And she's helped millions of people learn how to eat more and weigh less. I've known Barbara for a long, long time. And the other thing that is truly impressive about Barbara, her students and trainees have gone on to be the top researchers in this field. So if you look at who is really doing the best research in this area, there's a very good chance they were trained by Barbara Rolls. Barbara, welcome.

Barbara Jean Rolls:

Nice to be here with some good friends to talk about something close to my heart.

Holly Wyatt:

Yeah. So, Barbara, welcome to the show. And let's just start with the basics. What exactly is energy density and why is it so important when it comes to managing appetite, managing weight?

Barbara Jean Rolls:

Energy density defines as a scientist is the calories per gram of food. When I'm talking to the public, I like to have you think about it as the calories in each bite. If you pack more calories into each bite, for a given number of calories, you're going to get fewer bites. So it breaks down according to the macronutrients. Fat has nine calories per gram. Carbohydrate and protein, four calories per gram, so half as many. And fiber, about two to three. Now, what is new and what has really, I think, revolutionized thinking about how much food you can eat is that one of the biggest components if not the biggest in many of the foods we eat, is the water content. And that has no calories per gram. It adds weight and volume to foods. So it gives you bigger portions.

James Hill:

Barbara, you've done so much research in this area over the years. I'm going to put you on the spot. Tell us about like a couple of the kinds of studies you've done to show that energy density was a factor in weight management.

Barbara Jean Rolls:

I came off of studying fat and carbohydrate like most scientists in our field and looking at how they affected how much people would eat. So, varying the content, proportions of those macronutrients. And we started noticing that people in these studies were eating a similar weight of food. Why would that be? It doesn't necessarily boil down to the macronutrient content. It looks more likely that it's going to be something to do with the calories in that amount. So, we started systematically trying to dissociate energy density from the fat content. And you can do that by adding water-rich components to recipes. You can do this at home. Anybody can do it. You add more fruits, vegetables, maybe take a bit of fat out of a recipe, and you're going to have a recipe that's much lower in calorie density than you started with. So that's how we started. We would have people eating as much as they wanted out of dishes that were various energy densities over a couple of days, and found that people were eating similar weight and volume over these couple of days, but with the lower calorie density. You reduce calorie density by 30%, people are going to eat about 30% less over those two days. It persists. It's not just a short-term single meal phenomenon. And they felt just as full and satisfied. So that was really the key beginning of the studies, the seminal study.

Holly Wyatt:

Barbara, I've always wondered this. Is there a difference? Is it they're eating a constant weight or is it a constant volume?

Barbara Jean Rolls:

It's tricky. If you were just looking at liquids, you could dissociate that easier because it's easier to measure volume of liquid. I think it's a bit of both, honestly. But we just have a hard time measuring the volume of foods. When we've done studies just systematically varying volume, for example, by aerating foods, the volume does affect intake. But I think what's going on when we're eating is a complex interaction of visual cues, cognitive cues, the chewing, all of this. And all of those are affected by both the weight and the volume. The portion that you get affects how much you eat.

James Hill:

In the book, Volumetrics, there are tons of examples of different foods and diets differing in energy density. Give our listeners just a sense of high energy density foods, low energy density foods. What are some examples?

Barbara Jean Rolls:

In the Volumetrics books, we have four categories. It's a very low energy density, which are things like your fruits and vegetables, your non-high-carbohydrate fruits and vegetables, soups. Soups are great. Then as you gradually go up, you move through the four categories to finally the highest calorie density. And I think we all probably know what those are. They're higher in fat and they're dry.

James Hill:

Cinnabons. That's what it is.

Holly Wyatt:

Well, I don't know if Cinnabon's dry, Jim. Is it like dried fruit? But that didn't have high fat. It's dry.

Barbara Jean Rolls:

Things like cookies and crackers, even pretzels are pretty high energy density. It's the water content. Interestingly, you can have a diet that's high fat (this is your overall diet) but lower in energy density than a low-fat diet if that high-fat diet has lots of fruits and vegetables and the low-fat diet doesn't. So the impact of the water content on your total energy density and how much food you get to eat in a day is really enormous.

James Hill:

The water content is really interesting because, as you know, there's lots of research suggesting that calories and beverages may be regulated differently than calories in foods. So there's clearly something going on where water, which has no calories, may play an important role in regulating our food intake.

Barbara Jean Rolls:

Absolutely. And for me, it's kind of good karma because my research career started studying thirst. And now I get to study eating water. And this is the important thing. For the water to work, to affect hunger, you have to eat it, not drink it. One of my favorite studies we ever did was where we gave what we call a preload, a first course of different types of foods. And then you look at how much people eat at the next course. And in this, we had a casserole that was served either on its own in another condition with a 10 ounce glass of water. Another condition, the water was cooked into the casserole to make a soup. And we compared all those different conditions to what they ate when they had no first course. So, what do you think reduced intake at the next course the most? The soup and the casserole with the water have the same ingredients, just taking your water in a different form.

Holly Wyatt:

I'm going to go with casserole.

James Hill:

Yeah.

Barbara Jean Rolls:

Without, no, the soup had the...

Holly Wyatt:

Oh, but the casserole didn't have water in it.

Barbara Jean Rolls:

The casserole is the same casserole that is served with the 10 ounce glass of water.

Holly Wyatt:

Oh. I misunderstand it.

James Hill:

Oh, okay. You've got to have the water in the food.

Barbara Jean Rolls:

You've got to eat the water. That's the point.

James Hill:

Gotcha. I love it.

Barbara Jean Rolls:

Yeah.

Holly Wyatt:

And I think that is a really important point because so many people now are doing like protein smoothies and it has a lot of water in it. But what you're saying is eating the food and vegetables has a lot of water in them. People sometimes don't realize that there's water in vegetables and in fruit. That's how you need to get the water, not so much drinking it like in a smoothie. Is this is correct?

Barbara Jean Rolls:

Well, a smoothie, soups, they work pretty well. We've done studies where we've done a bunch of different types of beverages. This is the first course. And we still have a lot of good questions in our field to study. So why is soup super satisfying? And smoothies, we've used those in studies, and they're pretty satisfying too. But when you get to sodas, things like that.

Holly Wyatt:

Or just drinking a glass of water.

Barbara Jean Rolls:

Right, right. Yeah, other... Less, maybe viscous, who knows? Perception? A lot of it is, I think, cognitive too.

Holly Wyatt:

Yeah. Because I would think if you drank the water and then ate food, it's in your stomach. How is that different than a soup?

Barbara Jean Rolls:

Ah, okay. Well, the water that goes in as a beverage, first of all, it's going to trigger thirst rather than hunger, right? I mean, the systems are quite different biologically. But also there are studies, there have been biological studies that have followed up on our soup casserole study. And the unbound water empties out of the stomach much faster. So not as big a hit of gastric distension and filling you up.

Holly Wyatt:

So interesting. Very interesting. Complex.

Barbara Jean Rolls:

I like the message, eat your water.

James Hill:

That's a good message.

Holly Wyatt:

Eat your water. Yes.

James Hill:

All right. I have been looking forward to this episode because I want you to help me understand something I don't understand, Barbara. Everywhere I look, I see advice to not eat ultra-processed foods. What the heck is going on? And is avoiding ultra-processed foods different from what we've already been told to lower energy density and lower fat and sugar?

Barbara Jean Rolls:

Yeah, I think the public needs something to vilify, don't they? And they've just caught on to this term. Most people if you ask them what is an ultra-processed food, they won't really know for sure. By that definition, it's foods with lots of ingredients and basically boils down to sugar, fat, and salt, the sofas, as we call them, or as what I used to object to, junk food, which I think actually people understand better than the term ultra-processing. And I have to say, I've been on several committees now trying to figure out how to convey to the public and how to actually define what ultra-processed foods are. But if you take the NOVA categorization, which is the one that most of the studies are using, the highly processed ultra-processed foods tend to be high in sugar, fat, and salt, and higher in energy density, calorie density, and also easier to eat quickly.

James Hill:

Can processed foods actually be made to have low energy density? Is there a strategy there or is it sort of the opposite?

Barbara Jean Rolls:

Oh, sure. I mean, processing is simply the techniques that food scientists use to formulate and really talking about formulation of foods. So, yeah, they can aerate. They can use all kinds of calorie reduction strategies. You know, the issue is you have to make them palatable, tasty, and affordable. And you have to make people want them. This has been a problem. We know what needs to be done. We know what people should be doing. But getting people to do it is a big issue in our field.

James Hill:

So you don't think just making untasty foods is a good way to solve the obesity epidemic?

Barbara Jean Rolls:

I think there might be a little bit of pushback.

Holly Wyatt:

I want to switch a little bit because I know you can answer so many different questions. So I want to make sure I get my questions answered too. But what about variety and overconsumption and weight loss and kind of body weight regulation?

Barbara Jean Rolls:

I just actually published a review article called The Big Three, which are what we know most robust, most studied properties of foods that affect intake: energy density, portion size, and variety.

James Hill:

I love it, Holly. Those are the ones we talk about all the time. This is fabulous.

Barbara Jean Rolls:

You can look it up. It's in Physiology and Behavior. It came out, I think, last month. This month. It's just out. And we did a lot of the early studies on the variety, looking at what's called sensory-specific satiety. So as you eat a particular food, your hedonic, your liking response to that food declines. But interestingly, you still like other foods that are quite different in sensory properties. Where this has gotten a lot of traction with the press is this is why you like dessert. If you had a lot of salty, savory foods, you still like sweet foods. And then after we did those early studies, we looked at, well, okay, if you are tiring of one food and you still like others, then variety is likely to affect intake. So we did a whole series of studies on variety and how that affects intake and which properties. Just changing the shape of pasta, for example, over multiple courses affects how much you eat.

The interest in variety kind of waned over a number of years, and a couple of recent students that I've had here at Penn State have gotten back into looking at it. And they are proposing, Paige Cunningham, Nicholas Newell, working with Kathleen Keller, that perhaps what's going on in a varied meal is the switching between foods keeps you eating more. As you switch, you keep the interest in the different foods higher. And we indeed have done multiple studies now showing that switching, whether it's switching between a food and water or switching between multiple foods, does affect how much people eat. The more you switch, the more people eat. And we've done this in kids and some in adults. the Keller Lab has shown that the switching maybe is related to long-term weight gain over a year in kids. So this is a whole new area that's just opening up. And I think our recent students are going to continue working on this. So that is pretty exciting.

Holly Wyatt:

Yeah. Well, how about switching between vegetables? So one of the things I work out with some of the state-of-slimmers is they have one or two vegetables they eat and they get tired. And so one of the things we promote is let's eat a variety of vegetables to, I think, kind of keep them interested in vegetables. So I really would like them to eat vegetables. I would like them to get full on vegetables. Therefore, I'd like them to eat more vegetables. Therefore, that variety could work in your favor, maybe, I don't know, in that sense.

Barbara Jean Rolls:

Absolutely. We've done studies showing that the vegetables, you need to keep them relatively low in calorie density. But here's where cuisine comes in, different cooking methods, different preparation methods, herbs and spices, all of that can serve to maintain the interest in the food you're eating during a meal. The thing about getting people to eat more vegetables, and we've done a lot of studies on that, is you have to make them relatively palatable compared to the other foods available at the meal. So trying to do a study, and we do a lot of studies in three to five-year-olds, trying to increase vegetable consumption when they're competing against something like chicken nuggets is pretty tough. But competing against fish sticks, yeah, fish fingers, you can get the vegetable intake up. And you can use all of these different methods. You can combine portion size and variety add together. We've just done a study showing that. So, you can use these, the big three in combination to redo the plate if you like. That's really what we're thinking about, shifting the proportions of what you're eating.

Holly Wyatt:

I like this idea of it's not just one thing. It's energy density. Yes. And portion size. Yes. And understanding variety. And I like also that variety could work in your favor. We've been cooking vegetables in the State of Slim. I said, “Okay, here's 17 different vegetables I want you to try. Here's seven different ways to cook them. And here's 10 different seasonings to try on them.” So I think we can take this, the science that you've contributed so much, and you can use it in many different ways to help people really consume less calories over time.

Barbara Jean Rolls:

Yeah. And of course, this fits with the guidance from the government that you should redo the plate to increase the proportion of vegetables. And I really like that message because previously the message was just eat less. And that really is not very popular. Suddenly you're looking at a half empty plate and you're going to be hungry before you're going to start eating.

James Hill:

And it hasn't worked over decades, Barbara, where we've tried that. I love the big three. I want you to put in a plug. I know some of the work that you're doing and we're doing as well is how herbs and spices might be used to actually make vegetables a little more palatable.

Barbara Jean Rolls:

Absolutely. You, Jim, and your team have been doing some of the seminal work on that and using herbs and spices to reduce the calorie density, too. So instead of slathering lots of rich fatty sauces on foods, you can change the flavors, enhance the flavors, give a little kick to the trudge envelope, a little bit of chili, and just make them more interesting all around. And you've found, Jim, that it's a strategy that's working.

James Hill:

Yeah, the only problem, Barbara, is in America, we use salt and pepper, and that's about it. And there are so many other spices. So we urge people to play around with spices. Look at some recipes that involve different spices. You might be surprised at how you can modify the taste with different sorts of spices.

Barbara Jean Rolls:

I do think we have a lot more ethnic cuisines available now. When you look at the frozen food section, for example, there's a lot more variety there than there used to be 20 years ago. So I think people, as they get used to these different flavors, and there are a lot more different types of restaurants, they're going to be more receptive to this.

Holly Wyatt:

Yeah. So, I am a volume eater. Everybody who knows me knows I'm super sensitive. I think some of us are more sensitive to others, but I'm very sensitive to volume. What would you recommend for someone who's going to try to transition to a lower energy density diet? How would they start? Is there a way to transition to it or do you just rip off the Band-Aid and do it?

Barbara Jean Rolls:

Obviously, reading my books gives you lots of tips, but, you know, just don't try to give up your favorite foods. Figure out how to modify them. What are the tweaks that you can make to your favorite sandwich, for example, to lower the calorie density?

So, starting with the bread, swap out to the whole grain. Then with the contents, cut down on that massive pile of meat. Add more veggies. Try different spreads instead of mayonnaise, some sort of mustard or lighter spread, and experiment. Find something you like. If you don't like it and you're not enjoying it and you're feeling deprived, then you're never going to keep doing it. If you do that, you can decide. “Oh, I'm going to get a bigger portion with the same calories I usually eat.” Or if you want to just keep the portion the same and you've lowered the calorie density, you're going to get fewer calories. So it works both ways. The key really is just knowing these few simple strategies where you can add water, fruits and vegetables most of us are not getting enough, and where you could selectively reduce the fat, for example, the unhealthy fats. This is not recommending you go really low fat, but we get so much fat added to our foods, especially when we're eating out, that we really don't need. And I find actually I don't want. Often it's just too much.

So knowing these few strategies and then applying them to your favorite foods, I think is the place to start.

James Hill:

Barbara, I want you to address the elephant in the room in our field. The GLP-1 meds have changed things big time, and so people aren't hungry. So the challenges in nutrition are different from people on the GLP-1 meds. What's your thoughts about how to incorporate some eating strategies when you take these meds and you're not hungry?

Barbara Jean Rolls:

Yeah, I think it's really an intriguing time. I keep telling all my trainees, this is exciting because we really don't know how the big three are going to be influencing intake, for example, when people aren't feeling so hungry. My big worry about what's going on is that the caregivers may take the nutrition for granted and not incorporate as much. I've heard some say, “Well, the people aren't hungry, so why do we need to bother about that.” To me, it's going to be teachable moments. It's more important than ever to get people to be eating in a healthy way. They're going to need more nutrient-rich foods if they're eating less. We're finding that potentially they need more protein because of the muscle loss. So our advice may need to change. So it's exciting. We as the scientists working in this area, we need to step up. We need to figure out how to get the funding to look at these issues, and move it forward.

James Hill:

I agree totally. When you look out at what people are recommending that these people eat, there's almost no science behind it. We don't have the studies to know how to match nutrition to people on the meds.

Barbara Jean Rolls:

Hopefully we will get more. To me, it's where is the funding going to come from? Is pharma going to step up and fund these studies? They're already making satiety claims so I don't know if they feel the need.

James Hill:

Don't hold your breath on that one, Barbara.

Barbara Jean Rolls:

The government, should the government be funding these studies if the pharma is awash in money? The food industry, I think some of them will step up to try to figure out how to change their portfolio to meet the needs of the consumer.

James Hill:

I know the food industry is really concerned over this issue because they're trying to predict what people are going to be buying in the grocery store. So, I do think they have some reason to want to study this.

Barbara Jean Rolls:

Yes. Yes.

Holly Wyatt:

I think one term you used is important to kind of pull out and make sure people are understanding that it's different. We can talk about energy density, and it's different than nutrient density.

Barbara Jean Rolls:

Absolutely. And even nutrition professionals mix them up. The calorie density is about the calories, the energy content of a food, the nutrients. That's all the other fat, carbohydrate, vitamins, minerals, all the rest. And obviously, we need nutrient-rich diets. If we're managing your weight, lower calorie dense, more nutrient-dense. It's really important to keep those separate. And obviously, on these medications, people need nutrient-dense diets.

James Hill:

They do. So shoot for high nutrient density and low energy density in your diet.

Barbara Jean Rolls:

Yeah. I call it calorie density with the public because higher energy density sounds like a good thing, right?

James Hill:

Right, right.

Barbara Jean Rolls:

My first couple of books, I had to stick to energy density. It was ED, and that unfortunately overlapped with Bob Dole's ED. So that wasn't great timing anyway. But the third, more recent book switched to calorie density, just less pedantic. Let's just get to what the public understand.

James Hill:

There you go.

Holly Wyatt:

So less calorie, less caloric density, but more nutrient, which is vitamins and minerals and the things that you need for your body to work. And so really thinking about those two things, I think is important. How do I decrease the calories, but keep or increase the nutrient aspect of the diet.

Barbara Jean Rolls:

Right. And if you're eating less, you need to really focus on nutrient-dense food. So I think these medications if they're clobbering your hunger and making you feel full, you really need clear advice on what you should be eating or you're at risk for nutrient deficiencies.

James Hill:

Barbara, I know that in the last several years, you've started doing more work with children. What have you learned that could be tips for parents, particularly parents that might have children who worry about their weight?

Barbara Jean Rolls:

Yeah, we've done a lot of studies in three to five-year-old’s. We go into child care centers on campus and around the community and we manipulate their diets.

Our most recent ones were really ambitious, feeding kids for five days in a row all of their foods. In one, manipulating the portions served. In another, the calorie density of the food served. And in another, shifting the proportion of the plate towards more vegetables. So, the message from these studies is that the little kids are responding in the same way as the adults. It's thought that kids can self-regulate their intake. Well, maybe babies, but three to five-year-old’s over these five-day periods, if you give them bigger portions, they're going to eat more. If you give them higher energy-dense foods, they're going to eat more. If you give them lower energy-dense, they're going to eat more over the whole five-day period. And if you increase the proportion of fruits and vegetables they get, that's going to lower the calorie density of their diets. And particularly if you substitute those lower calorie-dense foods for the higher calorie-dense foods, they're going to eat less. And they're going to be eating a better balance of nutrients, a better diet. So the MyPlate recommendations work for little kids. The big three are valid in the little kids. I think that that's had some pushback from people that have been pushing this self-regulation idea for years. Don't count on kids resisting all of the goodies around your house.

Holly Wyatt:

Yeah, that makes sense. I think that's a great thing for the listeners to realize and to really think about the portion and what they're putting in front of their children, that it makes a difference in terms of how much they will eat.

Barbara Jean Rolls:

In terms of a little more advice, so, Jim, as your question, the parents really need to set the example. What the kids are doing early on is really setting them on a path to the sugar, fat, salt type of diet that adults like so much. So I think really trying to get kids eating a nutritious diet early on is extremely important, but they're not going to do it if you're not doing it.

Holly Wyatt:

Yes.

James Hill:

I love that. I'm so glad you brought it up. Despite what they tell them, they tend to mimic what we do.

Holly Wyatt:

All right. We've got some really good listener questions, Jim. Let's see if we can hit the whole list.

James Hill:

All right. Let's go for it.

Holly Wyatt:

All right. I'll go with the first one. This one's, I'm eating more volume, but I still feel hungry. What should I tweak? What can I do?

Barbara Jean Rolls:

Well, maybe just not getting enough calories. I hate to say it, but you do need the energy in there. And maybe you, I don't know, without knowing the specifics. Perhaps more nuts, protein, fiber.

Holly Wyatt:

Yeah. Try something else.

Barbara Jean Rolls:

Yeah. Obviously, none of us want to live just on soups and salads and fruit. You need some more substantial things to figure it out. And some of it could be cognitive, too.

Holly Wyatt:

Yeah. Maybe do you have enough protein in there?

Barbara Jean Rolls:

It's complicated.

Holly Wyatt:

Yeah.

Barbara Jean Rolls:

It's hard to give global advice.

Holly Wyatt:

So kind of a follow-up is, did you find a certain volume? Like, can you give us a number?

Barbara Jean Rolls:

No. No, and I don't want to, I mean, some people, they're trying to calculate the energy density of their total diets and such. I think this is about understanding the principles, you know, that you add the water-rich foods, you can tweak your unhealthy fats a bit, and you can make your diets bigger. Filling your plate in a satisfying way, it's knowing what foods work for you is really, once you've got these principles down, how to do it. And make sure that you enjoy what you're eating. If you don't have that satisfaction, if you have a feeling of deprivation, then this is not going to work. So focus on what you can eat, not what you can't eat, and then work around it, experiment with it.

James Hill:

Love it. Love it. Here's a question from a listener that wants to use energy density, but is worried about over-feeling their stomach. Is that a problem with low energy density?

Barbara Jean Rolls:

Oh, gosh. It's pretty hard to do that. I mean, there are some case reports of people with bulimia bursting in their stomachs. It's very, very rare. The stomach is very elastic. But obviously, you don't want to feel so stuffed that you kick it. Part of satiety is nausea if you look up the definition, then you don't need to eat to that point.

James Hill:

So you stop when you're full.

Holly Wyatt:

I think part of it is the stomach getting bigger and that feeling of the stomach stretching or overfilling is what kind of stops you, is the part of the satiety aspect of it.

James Hill:

Pay attention to are you full or not? Have you had enough? I love it.

Holly Wyatt:

All right. Here's a third one. And this one, this speaks to me a little bit. Can I still use these principles if I mostly eat frozen or packaged foods?

Barbara Jean Rolls:

Oh, sure. Yeah. I mean, most nutritious produce is frozen because it's frozen as soon as it's picked. And so, you know, it's constantly, yes, frozen produce is great. The principles would be the same. I think we need to try to nudge the food providers, the food companies to give us more low energy density packaged foods. We've done some studies with frozen meals and how they affect weight management as part of a big portion control trial. Most of the frozen meals, unless you're going for a hungry man or something like that, are pretty low in calorie density.

Holly Wyatt:

Yeah. I don't say that I cook very much so I do use a lot of frozen entrees. And the problem is to me, they're small volume. You're right. They're small calories and I've got my portion controlled, but they don't add enough volume for me. So I tend to add a bag of frozen vegetables. When I'm really hungry, I'll take whatever my kind of entree, my protein is gonna be. And I add a whole bag, I will say, of either the salad that's already been pre-cut up that's got everything in it or a frozen bag of veggies to get that volume that I tend to need.

Barbara Jean Rolls:

Yeah, absolutely. And some of them are not, for me, high enough in protein, fiber, with the other things. So, as you're suggesting, use them as a base and then bulk them out, use other frozen veggies or whatever, or have some fruit or yogurt with them. They've become much more versatile and much more diverse. And they worked pretty well in our clinical portion control trials, especially early on in the year-long trial. The people on the pre-packaged frozen portion-controlled meals lost weight much more quickly up front. They didn't have anything to learn. We were comparing it to the eat less kind of message or the strategically changing energy density. The other strategies, there's more learning curve. At the end of the year-long trial, all the portion control strategies we used worked, and people lost weight and kept most of it off. The problem was keeping the behavior going, like in any weight loss trial. People start off with a bang, and then at the six-month trial, there's usually a regain phase. So we need, as nutrition behavioral scientists, to figure out how to keep the maintenance going, how to keep the interest going in any of these strategies we're trying to develop for weight management.

James Hill:

That's been the problem, is the sustainability.

Holly Wyatt:

Yeah, and nobody wants to necessarily just eat prepackaged frozen meals in maintenance, right? They're willing to do it for weight loss to get the calories down, but is that really the solution for long-term weight loss maintenance?

Barbara Jean Rolls:

Well, there's some data that just doing it, say, for lunch can help. Again, it's boiling down to what you can sustain and what really is enjoyable for you or you're not going to keep doing it, and that's that. Giving up your favorite foods long-term is not going to work for people.

James Hill:

So, here's the question. Is there a simple way to estimate the energy density of what I'm eating? Do I need to take my calculator to the grocery store?

Barbara Jean Rolls:

No. If you look at the label on foods, it gives you the calories per serving. And if the calories are less than the grams, it's pretty low energy density and you shouldn't worry about it so much. So, in a hundred calorie serving, if a product has 70 calories, then that's pretty low calorie density.

James Hill:

That's a good tip.

Holly Wyatt:

Wait, so say that again. If the calories.

Barbara Jean Rolls:

Are lower than the grams in a serving.

Holly Wyatt:

In a serving.

Barbara Jean Rolls:

Because, you know, round one is where you start having to manage portions more because the energy density is going up. The energy density range is zero to nine. So just keeping that little tip in mind. It's very frustrating in America because every other country we found, except for Canada, the Nutrition Facts label gives you calories per 100 grams, which is such a great way to compare across food. So if you're, for example, wanting to eat a 100-calorie snack, if you looked at the label right away and you saw one has 150 grams and the other 100, you probably, for that 100 calories, want to go for the more volume, the bigger portion.

James Hill:

Great tips.

Holly Wyatt:

I got one more. We've been talking about this with some of our other episodes. Do you think it matters the timing?

Barbara Jean Rolls:

The timing of when you eat.

Holly Wyatt:

Yeah. So eating breakfast, eating, you know, should you be eating, really working on a volume strategy for breakfast or versus the evening meal?

Barbara Jean Rolls:

Yeah. It opens up so many questions related to snacking and how many meals a day you should eat and breakfast consumption. Jim's worked on breakfast consumption, I know. So many controversies in our field. Honestly, I think it boils down to what you as an individual find is the best pattern for you. Some people must have breakfast. I mean, you wouldn't want to be around me without breakfast. Other people don't really need it at all. They're fine snacking multiple meals a day. Again, you look at the science, it's six and one, half a dozen of the other. You really, in terms of giving advice, and I know people are frustrated about this, but it matters to you in how you best control your own hunger. And the nibblies. I mean, for me, my low period when I'm most likely to snack and eat things that I know in my head I probably should be eating less of, it's around three, four o'clock in the afternoon. I think that's pretty typical, but people are different.

Holly Wyatt:

Yeah, one size doesn't fit all. We definitely understand that message.

James Hill:

Okay, Holly, you know what time it is now?

Holly Wyatt:

It's vulnerability time.

James Hill:

You want to go first?

Holly Wyatt:

You can go first this time, Jim.

James Hill:

Okay. I've got a good one for you. I'd like to make these relevant to myself, Barbara. I will warn you. I've known you for many years. You've never been overweight.

Barbara Jean Rolls:

Uh-uh.

James Hill:

Since I've known you, okay. That's a different story. What do you prioritize in your diet, and how has that changed as you've gotten a little older? You and I are of a similar age, I think.

Barbara Jean Rolls:

Yeah. Well, I can tell you right now, it's easy for me because I am a gardener, and I am just swamped with tomatoes and zucchini and cucumbers and such. But I like fruits and vegetables. I have learned to really want them. I feel better if I'm eating right. One of the big changes I've made over my life is I went from regular soda to diet soda to water. And even the thought of soda now is it's not appealing. I do like wine. So that's definitely a vulnerability. And now as an older individual, I know I probably should be spreading my protein across the day more. But, you know, knowing too much, you can feel guilty all the time, which I don't want to do.

James Hill:

So you got to enjoy life.

Barbara Jean Rolls:

It's about it and enjoy what you're doing.

Holly Wyatt:

Yeah. All right. I'll ask one. In science, sometimes when we think we know something, we're sure of something. And then a little bit later, we figure out that wasn't exactly right. Science evolves and new studies come out and the field changes. What's something in the field that maybe you thought was one way that ended up being another? Something that kind of evolved over time that you changed your mind about?

Barbara Jean Rolls:

I think it goes back to where we started, which was the importance of the macronutrient content and particularly emphasizing shifting all the proportions of macronutrients around. And not to say that that can't matter. I mean, obviously, biologically, it's important. But when it comes to how much you eat, the calorie density overrides those differences. We've done a number of studies that show that. So, you need to focus on calorie density when you're looking at the macronutrients. And it's very frustrating to me that most of the big clinical trials that are still being done on macronutrients are not adequately assessing the effect of calorie density. It's a big frustration and something that I always like to point out. We need to know more about the effects of calorie density.

James Hill:

All right, Holly, let's sum up. You want me to take a shot at it and you can correct me if I get it wrong?

Holly Wyatt:

Yeah, that sounds like a good idea.

James Hill:

What I like in the episode is the big three that Barbara talked about on how you can avoid overeating. One is energy density or calorie density. And lots of data suggesting that lowering your energy density allows you to take the same volume or amount of food in with lower calories. So, it's a good way to manage your appetite. I will again plug the book Volumetrics. It is a wonderful book and it tells you so many ways to reduce your energy density. But one good rule of thumb for you in the grocery store, if the calories in a portion are less than the grams in a portion, that's probably a low energy dense food.

Second of the big three is portion size. And Barbara and others have done lots of data. The more food put in front of you, the more you eat. So managing portion size is number two in the big three. And the third one is variety. And that one's a little tricky because there are lots of ways that variety might actually cause you to eat more. The idea of you have a dinner and you still want a dessert. But we talked about some ways that variety, say, in fruits and vegetables and low energy-dense foods can be positive. So those are my takeaways, but there are things you can do that are going to help you take in fewer calories and be satisfied with it.

Holly Wyatt:

And I love “Eat your water.”

James Hill:

Eat your water.

Holly Wyatt:

Eat your water.

James Hill:

Eat your water.

Holly Wyatt:

That's what I'm going to take away from this.

Barbara Jean Rolls:

Yeah.

James Hill:

Barbara, this was terrific. Again, the work you've done in this field has just been exceptional for many, many years, and you're still out there doing wonderful stuff, and you've made such a contribution to our field. So thank you for sharing your time.

Barbara Jean Rolls:

It's a privilege to be with you. Thank you.

Holly Wyatt:

Thank you. Thanks, everybody. And please, if you have questions or topics, visit us at [www.weightlossand.com](http://www.weightlossand.com/). We would love to hear what you're thinking.

James Hill:

See you next time.

Holly Wyatt:

Bye, everybody.

James Hill:

And that's a wrap for today's episode of Weight Loss And. We hope you enjoy diving into the world of weight loss with us.

Holly Wyatt:

If you want to stay connected and continue exploring the “Ands” of weight loss, be sure to follow our podcast on your favorite platform.

James Hill:

We'd also love to hear from you. Share your thoughts, questions, or topic suggestions by reaching out at [weightlossand.com](http://weightlossand.com/). Your feedback helps us tailor future episodes to your needs.

Holly Wyatt:

And remember, the journey doesn't end here. Keep applying the knowledge and strategies you've learned and embrace the power of the “And” in your own weight loss journey.