Two Diets With The Same Calories Can Lead To Different Bodies

Ever wonder why two “identical” diets lead to totally different results? 

We dig into the thermic effect of food and the overlooked power of food structure to show how digestion cost, fiber, and processing change what your body actually gets from each bite.

 Calories don’t arrive for free, your body must work to chew, digest, and metabolize them, and that work varies by macronutrient and by how intact or processed a food is.

We break down why fat is cheap to process, protein is expensive, and carbs sit on a spectrum shaped by fiber and the food matrix. Then we zoom out to the real-world package: whole foods slow eating, engage satiety signals, and often deliver fewer net calories even when the label matches. 

Think whole nuts versus peanut butter, intact grains versus refined flour, and solid foods versus liquid calories. Randomized controlled trials back it up: when people eat freely, ultra-processed diets drive faster eating, higher energy density, and hundreds of extra calories per day, while minimally processed meals naturally curb intake without strict rules.

You’ll leave with practical, doable strategies. Build meals around plant proteins like beans, lentils, chickpeas, tofu, and soy. Favor fiber-rich fruits, vegetables, whole grains, nuts, and seeds that raise digestion’s energy cost and help you feel full on fewer calories. 

Choose solid over liquid when you can, and aim for an 80–20 balance that treats ultra-processed foods as a dose issue, not an enemy. Small differences in thermic effect and eating pace add up over months and years, nudging weight, metabolic health, and longevity in your favor.

If this conversation helped reframe how you think about calories and metabolism, follow the show, share it with a friend, and leave a quick review to help others find it. 

Got a swap you’re trying this week? Tell us, we love hearing your wins.

Go check out my website for tons of free resources on how to transition towards a healthier diet and lifestyle.

You can download my free plant-based recipes eBook and a ton of other free resources by visiting  the Digital Downloads tab of my website at https://www.plantbaseddrjules.com/shop

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Thanks so much!

Peace, love, plants!
Dr. Jules 

Transcript

Section A

SPEAKER_00 0:10

Yo, blind based buddies, welcome back to season three of the podcast. This year's gonna be amazing. We'll be talking about all of the different pillars of lifestyle medicine, from nutrition to exercise to stress to sleep and everything in between. Yo, blind based buddies, welcome back to another episode. Today we're gonna be talking about something that gets rarely mentioned when we're talking about metabolism, calories, weight management, or any part of your health journey. In the background, it's always there influencing energy balance every single day, but its impact are still small, but they can compound over the long term and play a meaningful role in anyone's health or weight management journey. Now, it's called the thermic effect of food. Sometimes it's referred as the thermogenic effect of food, but in simple terms, it simply describes how much energy your body has to spend to digest, to absorb, and to metabolize what you eat. Now, a lot of people think about calories as something that exists in food and something that food gives us. But extracting energy and calories from food also costs energy. Now, energy is stored in the chemical bonds that are in your food, and it you need to break these chemical bonds down so you can extract that energy back and re-invest it into the system. Now, the cost of doing that is not the same for all types of foods, and it's not even the same for all types of nutrients. And it's reasonable to want to understand this because there's a lot of confusion when it comes to nutrition debates. It might help it make more sense. Now, like I said, different macros require very different amounts of energy or amounts of work that your body needs to put in to extract that energy back. And dietary fat, that's the easiest of all macronutrients to process. Every gram of fat contains about nine calories, so it takes minimal energy to extract these nine calories from every gram of fat. Fat tends to kind of slip through digestion with very little effort, so its thermic defective food is sits at something like 0 to 5%. So that means that if you consume 100 calories of fat, almost all of these calories literally become available for your body. Now, carbs require a little bit more work. Remember that carbohydrate or carbs simply is an umbrella term that includes fiber, complex carbs, simple carbs, with the difference between complex and simple carbs being the amount of saccharides in that chain. So the thermic defect of carbs lands about 5 to 10% when considering all carbs included, but the body will need vastly different amount of energies to process fiber than to process simple carbs. Also, people don't eat carbs, they eat food. And so food is or carbs are part of a matrix, a complex matrix that includes vitamins, minerals, phytochemicals, fiber, and kind of other types of supporting cast chemicals that will either accelerate or slow down digestion and absorption of calories. And so if you eat 100% pure carbs or pure simple sugars, aka you drink white sugar from a glass, well, it's pretty easy to imagine that the thermic effect of that beverage or food, for example, drinking a soda, will be vastly different than the thermic defect of breaking down an apple and absorbing its calories. So when it comes to carbs, there are such big varieties of carbs, and carbs are also included in vastly different types of foods that the thermic defect is more difficult to predict when just trying to average it out. But keep in mind that whole minimally processed foods, on average, are more likely to contain fiber, to contain complex carbs, and with all of them being surrounded by a food matrix, meaning that your body will have a tougher time and needs to put more work in to extract these calories. And so this explains why the thermic defect of food, when it comes to highly processed or ultra-processed foods that are typically rich in carbs or in sugar, in fat and sodium, the thermic defect of food with that food will be vastly different than the thermic defect of whole, minimally processed plant foods that are rich in fiber and have an intact food matrix. Now, when it comes to protein, protein is in a completely different category. It has a thermic defect of food or a thermic defect of about 20 to 30%, but with the same thing as carbs applies to protein. People don't eat protein, they eat food. And food is a package that comes with a different ratio or combination of these macronutrients. So different ratios of protein to carbs to fat with either an intact or processed food matrix. But when it comes to pure protein, if you eat about 100 calories of protein, well, 20 to 30 of these will just get up used or burned up, trying to break down and metabolize the protein that you just consumed. Now, that amount alone is still meaningful, but it gets more interesting when we look at food as a package. Now, fiber-rich foods. So fiber is only containing plants, and when I'm talking about plants, I'm not talking about salads, I'm talking about foods that grow from the ground, from a tree or from a plant. So think about your fruits, your veggies, your legumes like beans, chickpeas, lentils, and soy products. Think about your nuts and your seeds and your whole grains, your herbs and your spices. These types of foods contain fiber. And fiber-rich foods increase the thermic effect of that food even further. And whole foods that contain fiber that still have intact cell walls and complex food matrix structures, they force your digestive system to work harder. Now, chewing takes effort and producing digestive enzymes that takes effort and it takes time and it consumes energy. And in that way, when you're eating whole intact foods, it's almost like absorption is less efficient, and your body needs to work harder and use more resources to extract minerals, vitamins, and energy from that food. So highly processed foods they behave very differently. Liquid calories require almost no effort. They're absorbed quickly, almost with a hundred percent efficiency. The the your digestive system barely needs to engage with that food to extract its energy. And that's where the difference between these two types of food are they become very clear when you look at different types of examples like this one. Take peanuts, for example. If you eat a handful of raw whole peanuts, they need to be chewed. Their cell walls will remain partially intact, their fiber and protein will limit how many calories actually get absorbed. Now, studies show that people, when they eat real whole, minimally processed nuts, they actually absorb a lot fewer calories than the label suggests. But if you compare whole nuts to peanut butter, well, peanut butter has already been mechanically processed. It's been degraded or broken down in microscopic pieces, the cell walls are broken before it even reaches your mouse. So as a result, 200 calories of peanut butter will likely lead to almost 200 calories being fully absorbed. It's the same food, it's the same label. The nutritional label will still say 200 calories, but their metabolic outcomes will be very different, and the amount of calories that you absorb will be very different too. Now, over time, these small differences matter. I'm not pretending that thermic effective food plays a huge role from day to day or meal to meal, but over weeks and months and years, the thermic effective food combined with how processed a food is can significantly change how many calories that actually enters your body every single day. Now, two diets with identical calorie counts on paper can still produce very different results in real life. Now, in this is not just my theory. We now have high-quality RCTs, randomized controlled trials, that show that this is playing out in real people in real life, but in controlled settings. They basically placed participants in a tightly controlled inpatient environment, and they gave them two different diets. One was based on ultra-processed foods, and the other one was based on minimally processed whole foods. Now, on paper, these diets were carefully matched. The same labeled calories, the same macronutrient breakdown, so the same amount of carbs, fats, and proteins, similar sugar, similar sodium, similar fiber, similar energy density. But the participants were allowed to eat as much as they wanted, also called ad libidum. They followed their own fullness and hunger cues and they stopped eating when they wanted. Now, but what happened in that study was still striking. When people were eating ultra-processed diets, they consumed about 500 more calories per day, on average, compared to when they were eating the unprocessed diet made of mostly minimally processed whole foods. Now, now, over just two weeks, they gained nearly a kilogram, more than two pounds of body weight, and those on the whole food diet lost about the same amount. There's also a Japanese crossover trial that found even larger differences. Participants ate over 800 calories per day more on the ultra-processed diet, and they gained more than two kilograms or almost five pounds in a week. They almost lost the same amount on the unprocessed version of that diet. Now, more recently, a longer eight-week trial in the UK showed greater weight loss on a minimally processed diet, even when boat groups were following healthy dietary guidelines and eating freely. So if you're asking, well, is it really the thermic effect of food that's kind of driving this? Well, at first glance, it's tempting to assume that ultra-processed foods somehow change how many calories that we absorbed or how fast our metabolisms run. But when researchers looked more closely, they kind of saw a different picture. They saw that ultra-processed meals are often eaten faster, they require less chewing, they kind of go down more easily, and they tend to lead people to build meals that are more energy dense. But on the whole food diet, people naturally selected meals that were larger in volume, sometimes more than 50% heavier by mass, but still lower in calories, mostly fruits, veggies, intact whole grains, and foods that are naturally rich in fiber. Now, in other words, they're not necessarily absorbing calories differently. Our stomachs can fit about 900 cc's, which are close to four cups, and regardless of the amount of calories you eat, most people eat somewhere between three to five pounds of food per day. But what if the energy density of that food is lower? You can still feel full, but eat less calories. Now, those that were eating ultra-processed foods, or I should say overeating ultra-processed foods passively, is probably more because of how those foods are structured, how quickly they can be consumed, and how little effort the body has to make to process them. So the thermic effect of these foods are low, but are just simply a part of why people tend to overconsume them and gain weight when most of their dyes contain ultra-processed foods. But when the scientists try to answer the question directly by controlling, strictly controlling calorie intake in so-called isochaloric feeding studies, then the evidence is more shady. There are no real long-term trials that really have measured whether ultra-processed foods change your net energy balance through differences in absorption or metabolic rate or oxidation when people eat the exact same number of calories. So that's where kind of the proof on thermic effective food kind of starts to become thin. Now there's one small short-term study that compared a whole food meal to a match meal replacement, and it found differences in post-meal termogenesis, but it only really looked at acute responses to a single meal, not really real-world eating patterns. There's another controlled feeding trial in young adults that provided dyes that were either mostly ultra-processed or entirely unprocessed, made from whole foods, but still mashed in calories and nutrients. And that study really didn't find any major differences for most participants. It really didn't even measure any significant change in weight or energy expenditure or absorption. So, where does that leave us and leaves the thermic defective food? It probably matters, but probably not that much unless you consider it over the long term. But still, all of that tells us something very important. The power of whole foods doesn't just live in their calories or the macronutrient ratios that they contain, it actually lives in their structure. Now, food is not just energy, it's texture, taste, it's chewing, it's the time it takes to process it and the work that your body needs to put into it to extract its energy. And that's where plant-based diets they shine. Plant proteins, they come packaged with fiber. So they retain a complex food matrix and they require more digestive effort. They deliver protein with a higher thermic defect of food while naturally slowing down how fast you eat and how many calories you passively consume. Plant protein doesn't just contain protein, which has a thermic defect of 20 to 30%, but also contains fiber, which is also at the higher end, probably 10% or more, when compared to other types of carbohydrates. So when you choose foods that are minimally processed, but still resemble how they exist in nature, meaning that the maybe the physical appearance of that food has been changed, but not the chemical composition, you just increase the metabolic cost of eating. And it supports your hunger signals and your fullness cues, and you kind of nudge your energy balance in a healthier direction. Not anything that'll be completely drastic, but more in a line with your own biology and physiology. So we're not talking about restriction, we are not talking about avoiding ultra-processed foods. Ultra-processed foods can absolutely be a part of a healthy diet. The issue is not the food, the issue is the dose. And studies show that anywhere from 40 to 60% of our daily calories, on average, are coming from ultra-processed foods, with probably around 30% coming from animal products and less than 5 to 10% coming from whole, minimally processed plants. So fruits, veggies, whole grains, nuts and seeds, legumes, herbs, and spices. If we look at the literature and try to find a good solid evidence-based balance, it'd probably be closer to something that people call the 80-20 rule. If 80% of your calories are coming from whole and minimally processed plants, then probably the 20% that's left over could come from almost any food, and you would still be in a good health balance. You'd still be kind of investing in your health because the amount of anti-inflammatory compounds in your diet are completely compensating for more of the pro-inflammatory compounds that are in either animal products or ultra-processed foods. So the goal is not avoiding certain food groups, but more working with your biology instead of working against it. And the thermic defective food, it just refers to the energy your body spends digesting and metabolizing what you eat. And we know that you'll just take advantage of higher energy costs if you're metabolizing whole, minimally processed foods that are rich in protein, rich in fiber, still just have a much higher thermic defect than highly processed foods that tend to be low in fiber, low in protein, but high in fat and sugar and refined carbs. Now, intact foods, they just require more work and they often lead to fewer net calories being consumed, even when the label is identical. Compare whole peanuts to whole peanut butter. Now, high-quality trials show that ultra-processed foods they tend to lead to passive overconsumption and to weight gain, largely because they not only have a lower thermic defective food, but they also are easier and faster to eat. Not because they fundamentally change your metabolism or absorption. Now, some of the practical tips I tell my patients to apply to their daily lives is just try to eat more foods that grow from the ground from a tree or from a plant. Prioritize foods that require chewing and digestion and try to eat them in a state as close to the way Mother Nature created them. Solid foods generally come with a higher thermic effect than liquids, but try to build more meals around plant proteins such as beans, lentils, chickpeas, tofu, soy products. And when you can combine these protein-rich foods that naturally contain high levels of fiber with other plants, you just become healthier, right? Now choose whole food versions over processed versions when you can. Whole nuts instead of nut butters, when considering calories, whole grains instead of refined flours, and just be cautious with liquid calories. Like even health, even smoothies that are considered healthy can absolutely be overconsumed and lead to excessive calorie intakes. But juices and shakes, they're even more easy to overconsume and to lead to high intakes of calories. So just think beyond calorie labels. Think about how the food you're eating is structured, how it changes your body, and how your behavior responds to those types of calories. Metabolism is not just about how you eat, but it's also about how much your body Needs to work to handle what you eat. So sometimes these foods, when you're eating whole foods, they naturally have a higher thermic cost, they naturally need to be chewed, they naturally lead to slower digestion, meaning that that fullness cue, which is still basic stretch receptors in your stomach, has time to get activated. You feel fuller sooner on foods that are lower in calorie density, that cost more to extract calories from. So over time, over weeks and months and years, that pattern of eating will not just deliver healthier foods that are more nutrient dense, typically they would lead to eating a dietary pattern that's lower in calorie density. But that tends to support weight, tends to support health, and tends to support longevity. Right on. I hope this makes sense. Thermic defective food is not often discussed, but I did want to cover it on a full episode so that people really understand how its benefits, if you understand them, can compound over time. Cool. Thanks so much for listening. We'll see you at the next episode. Peace. Hey everyone, go check out my website, plantbased drjouls.com, to find free downloadable resources. And remember that you can find me on Facebook and Instagram at Dr. JewelsCormier and on YouTube at Plantbased Dr. Jewels.