Boosting Metabolism
Published 6.17.2025: This presentation, from the vegan seminar, "The Truth About Weight Loss," was given by Dr Hana Kahleovah. The only notes that I took is that she says it's better to eat in the morning and skip dinner rather than vice versa… Which is fine an all, but I also have her slides, so I'll give my impressions of those as well.
An aside: I will note for the record that during my latest 5:2 "fasting" diet phase, what I did was skip breakfast and lunch, then eat a normal dinner. I did lose weight, and my "fasting" days were Tuesdays and Thursdays, because those used to be days off in terms of my going to the gym. However, I have starting using those days for "cardio"— meaning that I walk/jog on those days. Fasting doesn't seem to be a good idea— but the reason I stopped following the 5:2 didn't have anything to do with that.
I have kept the weight I lost off, but I haven't lost any more since upping my fiber content over skipping meals twice a week. I think that (and I have hard evidence in the terms of data) that my body composition is changing, but at least so far the scale is not changing. The "cardio" days only started after the New Year, so we'll see in a few months where things stand. End of aside.
So this talk is going to be how many times a day should you eat and when should you eat. I already gave a way the spoiler, the evidence she's about to go through suggests that eating in the morning and fasting at night is the best option. It's the scientific versions of the old saw: Eat like a king in the morning; eat like a lord at lunch (or a prince, I might have the rank wrong); and eat like a pauper at dinner. That does not fit with my lifestyle, so it's really a nonstarter for me.
I don't think Dr Fuhrman would disagree with this idea his teaching was to stop eating about 4 hours before bed. He though, doesn't really eat much at any meal, his schtick is calorie deficit with nutritional adequacy. His deal is that you should not feel hungry on his diet, after you get used to eating the way he says. And that dear reader is why nutritarianism is not the norm.
Dr Kahleovah points to evidence that multiple mini meals during the day have poorer glucose response than just having 2 meals. And she presents studies looking at late eaters vs early eaters. Early eaters (those that eat breakfast) had better blood glucose markers than those that ate later. For the record, the error bars in these studies are tiny. At least in these studies, the difference was real. Of course, she's not presenting all the evidence, and adherence is still the primary variable. Skipping dinner would not work for me, no matter the data. I would not adhere.
Weight loss was also found to be higher with folks who ate breakfast and lunch, rather than with those that ate 6 smaller meals— but that seems to me to be a calories in vs calories out issue. Did the 6 meal people eat the same number of calories as the two meal a day people? Or did they end up eating more because they had more opportunities to eat? She gives the reference, but I didn't bother to look it up before writing this. Mostly in these talks I'm just stating what they presented rather than trying to fact check them.
She claims that the people eating two meals a day were less hungry, and I can believe that— after they adjusted to the new eating pattern. I just don't think it's ever one I'd consider. And people who've lived very long lives have adopted two early meal a day plans— the trouble with this data point is that longevity is also genetic, and plenty of people who do not only eat two early meals have been long lived. There is no panacea, and long term adherence is still important. And (as in my case) adherence is going to depend on how your body reacts…
No surprise, people who snack tend to eat more and tend therefore to be heavier and have high blood glucose levels. Again, the energy balance is critical— I'm not saying that timing has no effect, but I'd first get my energy balance under control before I upended my lifestyle such that I don't eat at dinner. That might work for some, it will not for me.
She then presents (and these studies are hers, so she's done research in this area) that the more meals you eat, the higher your BMI (body mass index). Energy balance anyone? The more meals you eat, the more you eat, period. It still comes down to eating less (which I admit I'm still working on).
She then goes into intermittent fasting, which again (to my mind) comes down to how long you give yourself to stuff your face. Shorter eating window just means you have less time to eat, thus you eat fewer calories. And if your lifestyle supports that, more power to you. Every night I "fast" because I don't eat while I sleep. Most humans on the planet do the same, we just don't call it intermittent fasting. (I am not a fan of the intermittent fasting fad— and I do think it's a fad.)
She spends quite a bit of time on the thermic effect of food, which I will highlight because it was interesting and a little surprising to me. The thermic effect of food is only 10% of the total energy expenditure for the day— but it is the one that low carb zealots and keto fools hang their hats on. Per the data (not hers) that she presents: food eaten a dinner has a higher thermic effect than breakfast or lunch. And lean mass is metabolically more active than fat. This is where insulin sensitivity comes in. Leaner people tend to be more insulin sensitive over obese people.
Then she has a slide that seems to say that lower fat diets have a higher energy expenditure (thermic effect) than high fat diets, and that to me was surprising. Is that the effect of fiber? High fat diets can also be high in fiber, so perhaps not? Saturated fats (read animal products or coconut oil) have lower thermic effects than plant oils (poly- or mono- unsaturated fats). This result is also surprising to me. What's not surprising is that processed foods have less thermic effect than while foods (read plants).
And now we get into why the vegan diet is better than any when it comes to weight loss. This whole seminar was to push veganism, so none of this is surprising.
Bottom line: Don't skip breakfast, and if you skip a meal it should be dinner. Otherwise, in my opinion, it comes down to the energy balance and adherence. Find a way that you enjoy eating that will let you eat a bit less than you do. If that's a vegan diet, good for you. If it's not, still good for you.
DISCLAIMER: I am NOT any type of medical professional. Do NOT take medical advice from me!!
An aside: I will note for the record that during my latest 5:2 "fasting" diet phase, what I did was skip breakfast and lunch, then eat a normal dinner. I did lose weight, and my "fasting" days were Tuesdays and Thursdays, because those used to be days off in terms of my going to the gym. However, I have starting using those days for "cardio"— meaning that I walk/jog on those days. Fasting doesn't seem to be a good idea— but the reason I stopped following the 5:2 didn't have anything to do with that.
I have kept the weight I lost off, but I haven't lost any more since upping my fiber content over skipping meals twice a week. I think that (and I have hard evidence in the terms of data) that my body composition is changing, but at least so far the scale is not changing. The "cardio" days only started after the New Year, so we'll see in a few months where things stand. End of aside.
So this talk is going to be how many times a day should you eat and when should you eat. I already gave a way the spoiler, the evidence she's about to go through suggests that eating in the morning and fasting at night is the best option. It's the scientific versions of the old saw: Eat like a king in the morning; eat like a lord at lunch (or a prince, I might have the rank wrong); and eat like a pauper at dinner. That does not fit with my lifestyle, so it's really a nonstarter for me.
I don't think Dr Fuhrman would disagree with this idea his teaching was to stop eating about 4 hours before bed. He though, doesn't really eat much at any meal, his schtick is calorie deficit with nutritional adequacy. His deal is that you should not feel hungry on his diet, after you get used to eating the way he says. And that dear reader is why nutritarianism is not the norm.
Dr Kahleovah points to evidence that multiple mini meals during the day have poorer glucose response than just having 2 meals. And she presents studies looking at late eaters vs early eaters. Early eaters (those that eat breakfast) had better blood glucose markers than those that ate later. For the record, the error bars in these studies are tiny. At least in these studies, the difference was real. Of course, she's not presenting all the evidence, and adherence is still the primary variable. Skipping dinner would not work for me, no matter the data. I would not adhere.
Weight loss was also found to be higher with folks who ate breakfast and lunch, rather than with those that ate 6 smaller meals— but that seems to me to be a calories in vs calories out issue. Did the 6 meal people eat the same number of calories as the two meal a day people? Or did they end up eating more because they had more opportunities to eat? She gives the reference, but I didn't bother to look it up before writing this. Mostly in these talks I'm just stating what they presented rather than trying to fact check them.
She claims that the people eating two meals a day were less hungry, and I can believe that— after they adjusted to the new eating pattern. I just don't think it's ever one I'd consider. And people who've lived very long lives have adopted two early meal a day plans— the trouble with this data point is that longevity is also genetic, and plenty of people who do not only eat two early meals have been long lived. There is no panacea, and long term adherence is still important. And (as in my case) adherence is going to depend on how your body reacts…
No surprise, people who snack tend to eat more and tend therefore to be heavier and have high blood glucose levels. Again, the energy balance is critical— I'm not saying that timing has no effect, but I'd first get my energy balance under control before I upended my lifestyle such that I don't eat at dinner. That might work for some, it will not for me.
She then presents (and these studies are hers, so she's done research in this area) that the more meals you eat, the higher your BMI (body mass index). Energy balance anyone? The more meals you eat, the more you eat, period. It still comes down to eating less (which I admit I'm still working on).
She then goes into intermittent fasting, which again (to my mind) comes down to how long you give yourself to stuff your face. Shorter eating window just means you have less time to eat, thus you eat fewer calories. And if your lifestyle supports that, more power to you. Every night I "fast" because I don't eat while I sleep. Most humans on the planet do the same, we just don't call it intermittent fasting. (I am not a fan of the intermittent fasting fad— and I do think it's a fad.)
She spends quite a bit of time on the thermic effect of food, which I will highlight because it was interesting and a little surprising to me. The thermic effect of food is only 10% of the total energy expenditure for the day— but it is the one that low carb zealots and keto fools hang their hats on. Per the data (not hers) that she presents: food eaten a dinner has a higher thermic effect than breakfast or lunch. And lean mass is metabolically more active than fat. This is where insulin sensitivity comes in. Leaner people tend to be more insulin sensitive over obese people.
Then she has a slide that seems to say that lower fat diets have a higher energy expenditure (thermic effect) than high fat diets, and that to me was surprising. Is that the effect of fiber? High fat diets can also be high in fiber, so perhaps not? Saturated fats (read animal products or coconut oil) have lower thermic effects than plant oils (poly- or mono- unsaturated fats). This result is also surprising to me. What's not surprising is that processed foods have less thermic effect than while foods (read plants).
And now we get into why the vegan diet is better than any when it comes to weight loss. This whole seminar was to push veganism, so none of this is surprising.
Bottom line: Don't skip breakfast, and if you skip a meal it should be dinner. Otherwise, in my opinion, it comes down to the energy balance and adherence. Find a way that you enjoy eating that will let you eat a bit less than you do. If that's a vegan diet, good for you. If it's not, still good for you.
DISCLAIMER: I am NOT any type of medical professional. Do NOT take medical advice from me!!