Are certain foods more fattening than others?
Could you eat in a way that will make you less likely to gain body fat?
There is a lot of nuance to these questions, for the most part though I don’t think specific foods will cause you to gain body fat while others won’t.
Ultimately it is your caloric balance that dictates whether you will gain, lose, or maintain body fat. However there are foods that can make it harder to consume too many calories and foods that make it easy to consume more calories. There may also be foods that impact things like your digestion, your sleep, your physical activity and your hormones all of which play a role in how many calories you do or do not burn.
Rather than look at individual foods and discussing whether they are bad or good I would rather look at broad categories of foods as it makes it easier to discuss and provides a high level overview of many different foods. Since all foods are made up of fat, carbohydrates and/or protein I think it’s best to discuss if any of these foods are more or less likely to cause body fat gain.
Let’s kick off the discussion with fat.
Dietary fat makes you fat!
Makes sense right? Why wouldn’t fat make you fat?
We have been warned again of the dangers of fat for decades now, and as with most things in nutrition, the pendulum swung in the low fat direction and we were marketed tons of low fat foods.
Ultimately dietary fat will only accumulate as body fat if you eat too many calories.
That said, dietary fats do have a few things that work against them when it comes to accumulating body fat.
Since body fat accumulation is dictated by caloric intake we should point out that fat is more calorically dense than carbohydrates and protein. One gram of fat has 9 calories, while protein and carbs contain 4 calories per gram. Given that, a little fat goes a long way from a calorie point of view. Our bodies seem to recognize this fact as well, foods that have more fat in them are generally more palatable to most people.
Think about it, what would you rather eat: a chicken breast or a chicken wing? Most people will choose the chicken wing hands down.
Why?
It’s fattier.
From an evolutionary perspective this makes a lot of sense because we needed as many calories as possible to survive. Eating fattier foods makes evolutionary sense when calories are hard to come by. For many of us, calories are not hard to come by today, so our desire for fattier foods works against us.
While I have nothing against whole natural fat sources, we just need to be cautious with them. Of particular concern are the added fats, the ones we add to our foods to improve the taste. Things like butter, any kind of oil (olive, avocado, nut oils, etc), cooking fats like tallow and lard, the nuts and seeds you use for that added crunch or for a snack, grain free flours made from nuts and seeds, paleo/keto/primal salad dressings (which generally have some kind of oil as a base). All of these foods would be considered healthy and to some that means they can be consumed without any kind of oversight. They certainly can be healthy, but if you consume them with reckless abandon the calories add up, and add up QUICK!
Outside of the fact that fats are more calorically dense and our bodies tend to prefer high fat foods, dietary fats are also more easily stored as body fat than protein and carbohydrates. Protein and carbohydrates can certainly be stored as body fat when consumed in excess (although protein less so more on this later), however the body needs to convert them to triglycerides to do so. This takes energy which means the net energy that gets stored as body fat is less.
In contrast, dietary fat is more easily converted to triglycerides and therefore the net energy stored as body fat is greater (Hill, n.d.). The graph below is taken from an overfeeding study which looked at the amount of energy stored from consuming excess energy from fat versus carbohydrates. As you can see nearly all the energy from excess fat consumption gets stored while excess carbohydrates is less.
If you don’t believe fats can make you fat then you probably believe carbohydrates can.
The narrative behind carbohydrates and body fat is that carbohydrates cause an increase in insulin. Insulin turns off your body’s ability to burn fat for energy hence you can’t release your stored body fat to be burned and therefore you can never lose body fat and can only add to your fat stores.
Seems simple right?
Unfortunately it is not that black and white. If you don’t consume more calories than you are burning your body will find a way to use your body fat store to provide the energy you need, regardless of your insulin levels. Several studies have shown that regardless of the carbohydrate content of a diet, if you are in an energy deficit you will lose weight.
Carbohydrates are also your body’s preferred fuel for energy, especially when it comes to intense physical activity (although even low intensity physical activity will burn carbohydrates). When you consume carbohydrates the first thing your body is going to do is replenish its stores of carbohydrates in your muscle and liver to make sure it has its reserves topped off in case you need to run from a tiger. This is one of the many reasons why having more muscle mass is beneficial, it provides you more places to store carbohydrates without having to convert them to fat. In addition, this is why physical activity is so important. Since carbohydrates are used for energy, if you consume carbohydrates and then do something physical your body will use those carbohydrates to fuel that movement.
However once your carbohydrate stores are full and you continue to eat carbohydrates beyond your caloric needs then the body will end up storing the excess not in the muscles but as fat. The body converts the carbohydrates to triglycerides and stores them in your fat stores through a process called de novo lipogenesis (which means creation of new fat) (10.4: Lipid Metabolism, 2022)
https://www.youtube.com/watch?v=Lnu2k6ZsNb4
This brings us to the final macronutrient, protein. Protein is probably the most interesting macronutrient when it comes to fat storage. The reason it is so interesting is that there have been a number of protein overfeeding studies and many of them show that you can consume large amounts of extra calories in the form of protein and many individuals tend to gain little fat or actually lose body fat! That is kind of mindblowing, and also is a prime example of a calorie is not a calorie.
First it is important to realize that we don’t really store protein in the body like we can carbohydrates and fat. Excess protein will either be excreted in the urine or if the body needs additional glucose (the name for the stored form of carbohydrates in the body) it can convert protein to glucose via a process called gluconeogenesis.
In addition protein has the highest thermic effect of food, meaning when compared to fat or carbohydrates protein takes more energy (aka calories) to digest.
5 Simple Ways to Make Weight Loss Easier Through Nutrition
Given these facts it is then not terribly surprising that when we look at many of the protein overfeeding studies we don’t see body fat gain from protein in the same way we do when people overfeed on fat or carbohydrates (The Effects of Overfeeding on Body Composition: The Role of Macronutrient Composition – A Narrative Review, 2017). In general the same research also shows that if you consume extra calories from protein AND do strength training you will be more likely to add muscle. And if you remember what I said above in regards to muscle and carbohydrate intake, this will also help insulate you from accumulating body fat from excess carbohydrates!
As you know, I always like to provide the science but also leave you with some practical recommendations to put to work, so let’s wrap up this post with my thoughts on how to put this information to use.
First and foremost as I stated at the beginning of this blog no food in isolation is going to add body fat. You must be consuming more calories than you are burning in order to add body fat. Twinkies may not be the best choice when it comes to food, but I won’t deny the fact that if you can manage to control your calories while eating Twinkies you won’t put on body fat. This is essentially the idea behind the “if it fits your macros” movement…eat whatever you want as long as you adhere to your macros you will reach your goal. I personally don’t believe that is the best approach for many people for two reasons: it’s hard to implement and also there is more to health than calories. That said, it is clear that some people can be successful with an if it fits your macros approach….at least in the short term.
Knowing that, if your goal is not to gain body fat and the key factor is calories, we need to look at the foods that are likely to cause you to consume more calories than you need.
Number one on that list is ultra-processed foods.
I don’t spend a ton of time on this topic because I have written about the negatives of ultra-processed foods in terms of body fat numerous times before.
To summarize, here are some of the key reasons why ultra-processed foods make it easy to consume more calories than you need:
- They are calorically dense, meaning they contain a large amount of calories for not a lot of food. This makes it easy to eat and not feel full.
- They also light up our brain, meaning the taste, texture, mouth feel, and appearance get our brain excited and wanting more.
- They don’t contain much in the way of nutritional value so they do little to satisfy our nutritional needs. This leaves your body telling you to consume more to fill the void.
- They don’t do much to slow down digestion, in fact many ultra-processed foods are very easy to digest meaning you will be hungrier quicker.
- They can cause blood sugar crashes causing you to seek out more food to correct the imbalance.
I also want to be clear that all “diets” have versions of ultra-processed foods. Just because you are consuming an ultra-processed food item that is keto/paleo/gluten free/vegan/vegetarian it doesn’t mean that it is somehow inherently better than the conventional version. Sorry…but a cupcake is still a cupcake no matter what diet it conforms to.
I am also going to throw liquid calories into the category of ultra-processed foods. You might be thinking, well of course the slurpee and the “coffee” drinks you get from the cafe are ultra-processed. However I would also lump things like butter coffee/tea and shakes into this category as well. It is very easy to consume 500 calories worth of butter in your coffee or tea and to consume a 1000 calorie smoothie. Those calories go down quick and easy and require minimal effort to digest. Unless you are purposely trying to gain weight, I would not suggest them.
Next we need to look towards whole foods that are in their natural form and are also easy to overconsume. This is where there is going to be some nuance because everyone is different in what they enjoy.
For some people fruit is very easy to overdo, for other nuts and seeds, for others it is dairy, for others it is fat. I encourage you to think about your favorite whole foods, the ones you can eat a ton of. If you can put down a whole rack of ribs, eat a whole wheel of cheese, eat a bucket of chicken wings, eat a whole bag of roasted nuts and not think twice about it, those are the foods you need to have some oversight with. You might not weigh and measure everything but I would highly suggest you weigh and measure out those foods you can eat with reckless abandon to make sure you are not overdoing it.
Weigh 4 oz of ribeye, just have 1-2 ribs, have 3 wings, measure out an ounce of nuts or dairy (or you can use hand measurements as well). Again there is nothing “bad” about these foods. What is bad is when there is no “off switch” for a food, whether that food is ultra-processed or a single ingredient food.
Finally I want to make it clear that your overall lifestyle, not just the foods you eat, play an important role in whether you are going to gain body fat or not. For example, if you get a bad night’s sleep you might be more likely to have a dysregulated appetite the next day, or succumb to the donuts in the breakroom, or snack throughout the day. We also talked about how exercise can play an important role in how you metabolize your food, particularly carbohydrates. In addition exercise can help you regulate your appetite and make it less likely that you overeat. Stress also plays an important role in people’s cravings, desires, and food preferences.
And as always we can’t ignore the importance of how lifestyle helps regulate our hormones and how hormones can play an important role in our food preferences as well as how we metabolize foods.
So while caloric balance plays a key role in whether we gain body fat or not, it is not nearly as simple as calories in and out, and it’s not as simple as this food is fattening and this food is not. We need to consider a lot of factors that all work synergistically to regulate how our body responds to the foods we eat. This is why I stay away from black or white thinking and instead rely on an ancestral model of health to help guide us in the right direction to our goals. If you would like more nuanced information on how to reach your goals sign up for my newsletter using the form below and get ready to receive weekly free information to get you to where you want to be.
References
The Effects of Overfeeding on Body Composition: The Role of Macronutrient Composition – A Narrative Review. (2017, December 1). NCBI. Retrieved October 10, 2023, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5786199/
Hill, J. (n.d.). Fat and carbohydrate overfeeding in humans: different effects on energy storage. PubMed. Retrieved October 9, 2023, from https://pubmed.ncbi.nlm.nih.gov/7598063
10.4: Lipid Metabolism. (2022, July 30). Biology LibreTexts. Retrieved October 10, 2023, from https://bio.libretexts.org/Courses/Lumen_Learning/Anatomy_and_Physiology_II_(Lumen)/10%3A_Module_8-_Metabolism_and_Nutrition/10.04%3A_Lipid_Metabolism