There has been a rise in the popularity of low-carbohydrate diets over the last decade, and they became one of the most popular diets of the previous five years. The increase in popularity was due to the idea that carbohydrates control your body fat, with the more carbs you consume, resulting in more fat being added to your body. While this is what many popular diet books and media channels have stated, what does the science tell us?
We can find out if carbohydrates control body fat by asking a few key nutrition questions, which we will dive into.
Are people who consume more carbs likely to have more body fat?
This has been studied quite extensively, and the results do not seem to support the idea that carbohydrates per se control body fat. For example, in one study of ~4,500 people, there was a lower risk of being obese or overweight if you consumed a moderate to high carbohydrate diet when compared to a lower carbohydrate diet. Another study found that there was no real association between BMI and daily carbohydrate intake, suggesting that if carbohydrates did control body fat, it would be a relatively minor effect.
So when we look at people’s eating habits and whether or not they correlate with body fat, it is hard to say that carbohydrate intake controls body fat. However, this is just one question to answer; there are a few more that we need answers to as well.
Are carbs more “fattening” than fats?
If carbohydrates did indeed control body fat, then we would expect that low-carb diets are less “fattening” than higher carbohydrate diets. This means that low carb diets should add less body fat to people than higher carbohydrate diets do. As such, we should ask ourselves if carbohydrates are indeed more “fattening” than dietary fat.
Over the last decade, there has been a lot of commentary indicating that overeating carbohydrates leads to storing calories as body fat. This is true in the most basic sense in that when you overconsume calories. You do store at least some of the excess. But it turns out that excess carbohydrates are relatively difficult to store, at least compared to fats. For example, in one study where people were overfed carbohydrates and fats, fats were stored ~20% more efficiently than carbs. In another study where people were overfed carbohydrates, there was a very minimal conversion of carbohydrates to stored body fat, indicating that it is very inefficient to turn carbohydrates into fat.
Ultimately, science tells us that carbohydrates are not more fattening than fats; in fact, it would make more sense to eat a few too many carbohydrates than a few too many fats. Indeed, this is what we see when we follow people who over-consume carbohydrates versus fats - they tend to gain a little less body fat.
Are low-carb diets better for weight loss?
The next big question is whether low-carb diets are better for weight loss than other diets that are higher in carbohydrates. Well, thankfully for us, this has been studied extensively over the past several decades.
First, when you tightly control people's diets and measure virtually every part of their metabolism, it is apparent that low-carb diets are not better for weight loss. They might be slightly worse for body fat loss than low-fat diets. This holds true even if you go to very low levels of carbohydrate intake.
Second, when you adopt a low-carb diet in the real world and over more extended periods, we still see very similar results. The majority of the clinical trials that have examined whether low-carb diets are better than other diets for fat loss show that low-carb diets result in the same amount of weight loss as other diets.
The Wrap Up
Although the idea that carbohydrates control body fat has been popular in the media, there is little scientific evidence to support it. Unless you have extreme levels of carbohydrate intake, there is no real link between carbohydrates and body fat. Additionally, when you conduct careful scientific experiments, it turns out that carbohydrates are less fattening than dietary fat. When followed in the real-world, low-carb diets can be useful for weight loss, but they are not any more effective than other calorie matched diets.