Volumetrics… water over fiber?
Published 4.15.2025: This was the first talk where I copied the slides rather than taking notes. The presenter was Dr. Barbara Rolls, she wrote the book about volumetrics. Volumetrics is the idea that low calorie dense foods are the best to eat, because you get more volume for the calories. The stomach is fuller on less calories and it's bulging size indicates that the it is full. That is NOT how a professional would describe it, that is my understanding and layman's definition.
I am quite fond of volumetrics as a way to eat and lose weight, because I am a volume eater, meaning I like my stomach to feel full. It's the volume of food that registers with me, rather than the total calories. Part of the reason I don't like low carb diets is that on that diet my stomach was never full, despite meeting the calorie limits of the diet— and YES Virginia, low carb diets only work if that way of eating results in you eating FEWER calories. No one (or no diet) escapes the energy balance.
Anyway, before Rolls got started, AJ stated that it was her work that caused her to understand calories and lose the weight— but back in 2015, she credited Dr McDougall and his way of eating. Now, it's entirely possible that both diet methods influenced her, but I found it interesting for Dr Rolls to be credited with her weight loss.
Rolls is a very interesting and prolific researcher. She started by invoking the "big 3" that influence weight loss: Portion size, calorie density and variety. There are other factors with influence as well, but she's going to focus on these three.
The first topic is portion size, which has increased since the 1950s, and particularly since the 1980s. Her research has shown the increased portion sizes don't register with people— if it's on the plate it must be a portion and so let's eat it all. Offering "doggie" bags only slightly shifted the amount that people ate, it still increased as portion sizes increased.
What doesn't matter at all? Plate size. Offering people smaller plates just meant that they went through the buffet line more times. Similarly, smaller dinner plates just mean that people serve themselves most times. I don't think that people tend to serve dinner as a restaurant would— though restaurant portions are where the problem began.
High end (think Michelin-starred) restaurants tend to serve much smaller portions, though perhaps more of them if you're doing a tasting menu. I think they get away with it because part of what you're paying for is "the experience." Typical (lower end) restaurants can't do that. In fact, many people expect the portions to be huge, or they don't think they've gotten their money's worth. Should be fascinating to watch what happens as prices continue to rise…
Calorie density is next. Do different macronutrients change how people eat? The answer there is yes… generally protein is thought to be more filling. Fiber doesn't get a whole lot of love from Rolls, she says the effect is moderate. What does matter is water in foods (which favors plant foods, I would think). She says you should, eat your water as well as drink it. Soups (broth based) are what she means here. Drinking actual water while eating actually caused people to eat more. Certainly I find that I eat more if I'm also enjoying a glass of wine (which is mostly water).
The largest effect in terms of calorie density is eating less fat. Fat has 9 calories per gram, so that makes a lot of sense. She is not talking about health, just talking about how many calories are ingested. Interestingly, lowering sugar is found to have only a moderate effect (the same as fiber). The original definition of hyper-palatability didn't include sugar… it's not the sugar we're craving, it's the fat that typically comes with it.
The fact that fiber isn't the primary factor is surprising to me, that is not what I expected. Now, most foods with the highest water content are going to be fruits and vegetables, and those are also highest in fiber. But they must have found a way to separate them, because she was adamant that eating your water was more important than maximizing fiber.
Basically if you reduce fat and eat more fruits and vegetables, you will lose more weight. Given the above, these results are not surprising.
Next up is food variety. I think her point here was that people tend to eat more when there are more choices to be made. I think I've heard this from Stephan Guyenet, who says that a boring diet (eating the same thing daily) is the way to lose weight. Sounds very boring to me, and I wouldn't want to live that way.
It's in this section that she presents her results that not drinking water between bites results in lower overall calorie intake. Even with vegetables, if you have more options, people wind up eating more. This could be called the "Thanksgiving" effect (at least here in the US)— people take "just a bit" of everything, and wind up with more food than they would typically eat.
Her final advice amounts to: eat your water, choose foods that are not calorie dense (which would lead you towards plants naturally) and portion control. Portion control echoes Marion Nestle — we are fat because we eat too much.
This was a very interesting talk, and I think I might need to read some of Barbara Rolls research. She is not vegan, so there was no emphasis in this talk on the need to avoid all animal foods. But her notation that fat, and particularly saturated fat, needs to be minimized, means minimizing animal products, because that's where most saturated fat is in the food supply.
DISCLAIMER: I am NOT any type of medical professional. Do NOT take medical advice from me!!
I am quite fond of volumetrics as a way to eat and lose weight, because I am a volume eater, meaning I like my stomach to feel full. It's the volume of food that registers with me, rather than the total calories. Part of the reason I don't like low carb diets is that on that diet my stomach was never full, despite meeting the calorie limits of the diet— and YES Virginia, low carb diets only work if that way of eating results in you eating FEWER calories. No one (or no diet) escapes the energy balance.
Anyway, before Rolls got started, AJ stated that it was her work that caused her to understand calories and lose the weight— but back in 2015, she credited Dr McDougall and his way of eating. Now, it's entirely possible that both diet methods influenced her, but I found it interesting for Dr Rolls to be credited with her weight loss.
Rolls is a very interesting and prolific researcher. She started by invoking the "big 3" that influence weight loss: Portion size, calorie density and variety. There are other factors with influence as well, but she's going to focus on these three.
The first topic is portion size, which has increased since the 1950s, and particularly since the 1980s. Her research has shown the increased portion sizes don't register with people— if it's on the plate it must be a portion and so let's eat it all. Offering "doggie" bags only slightly shifted the amount that people ate, it still increased as portion sizes increased.
What doesn't matter at all? Plate size. Offering people smaller plates just meant that they went through the buffet line more times. Similarly, smaller dinner plates just mean that people serve themselves most times. I don't think that people tend to serve dinner as a restaurant would— though restaurant portions are where the problem began.
High end (think Michelin-starred) restaurants tend to serve much smaller portions, though perhaps more of them if you're doing a tasting menu. I think they get away with it because part of what you're paying for is "the experience." Typical (lower end) restaurants can't do that. In fact, many people expect the portions to be huge, or they don't think they've gotten their money's worth. Should be fascinating to watch what happens as prices continue to rise…
Calorie density is next. Do different macronutrients change how people eat? The answer there is yes… generally protein is thought to be more filling. Fiber doesn't get a whole lot of love from Rolls, she says the effect is moderate. What does matter is water in foods (which favors plant foods, I would think). She says you should, eat your water as well as drink it. Soups (broth based) are what she means here. Drinking actual water while eating actually caused people to eat more. Certainly I find that I eat more if I'm also enjoying a glass of wine (which is mostly water).
The largest effect in terms of calorie density is eating less fat. Fat has 9 calories per gram, so that makes a lot of sense. She is not talking about health, just talking about how many calories are ingested. Interestingly, lowering sugar is found to have only a moderate effect (the same as fiber). The original definition of hyper-palatability didn't include sugar… it's not the sugar we're craving, it's the fat that typically comes with it.
The fact that fiber isn't the primary factor is surprising to me, that is not what I expected. Now, most foods with the highest water content are going to be fruits and vegetables, and those are also highest in fiber. But they must have found a way to separate them, because she was adamant that eating your water was more important than maximizing fiber.
Basically if you reduce fat and eat more fruits and vegetables, you will lose more weight. Given the above, these results are not surprising.
Next up is food variety. I think her point here was that people tend to eat more when there are more choices to be made. I think I've heard this from Stephan Guyenet, who says that a boring diet (eating the same thing daily) is the way to lose weight. Sounds very boring to me, and I wouldn't want to live that way.
It's in this section that she presents her results that not drinking water between bites results in lower overall calorie intake. Even with vegetables, if you have more options, people wind up eating more. This could be called the "Thanksgiving" effect (at least here in the US)— people take "just a bit" of everything, and wind up with more food than they would typically eat.
Her final advice amounts to: eat your water, choose foods that are not calorie dense (which would lead you towards plants naturally) and portion control. Portion control echoes Marion Nestle — we are fat because we eat too much.
This was a very interesting talk, and I think I might need to read some of Barbara Rolls research. She is not vegan, so there was no emphasis in this talk on the need to avoid all animal foods. But her notation that fat, and particularly saturated fat, needs to be minimized, means minimizing animal products, because that's where most saturated fat is in the food supply.
DISCLAIMER: I am NOT any type of medical professional. Do NOT take medical advice from me!!