The battle between fat and sugar has been raging for decades. Overindulging in both can lead to weight gain, but the real question was which was the main culprit? The case has seemed open and shut since the 1970s, when the United States government released dietary advice recommending a low-fat diet.

However, that wisdom is now open to debate, leading scientists to take a second look at the relationships fat and sugar have with weight gain. Their findings have shaken common dietary wisdom up.

Sugar or Fat?

A primary reason we believe fat and sugar lead to weight gain is because both are independently true, though only in the most simplistic sense. If you recall from our analysis of macro counting, fat has the most calories per gram of all the other macronutrients. If you’re eating fat-heavy foods, it will likely lead to weight gain. The same can be said for sugar-heavy foods like desserts and candies. As such, both are bad in excess.

Fat’s so important to flavor that many low-fat “diet” foods load up on sugar to make the dish taste better.

You may wonder why it seems like there’s a dichotomy between sugar and fat. Surely, there can be both a low-sugar, low-fat option out there. These tend to be vegetables, grains, or beans, among others. But if you’re cooking them, there’s a good chance you’re adding fat or sugar since both are important to flavor and cooking. In fact, there are few recipes that don’t call for a fat of some kind, since oil is a fat. It’s so important to flavor that many low-fat “diet” foods load up on sugar to make the dish taste better. Unfortunately, many dieters see the low fat and think “so what if it’s high in sugar, it’s low in fat!”

Herein lies the problem. Recent research shows that it’s sugar, not fat, that’s the true culprit for weight gain. So, if you’ve been cutting fat out of your diet, but overindulging in sugar, even in sneaky places like low-fat foods or your morning coffee, you may be sabotaging yourself!

Why Sugar Makes You Gain Weight

The evidence has been mounting for how damaging sugar can be to your physique. One study from 2013 analyzed 30 clinical trials to find links to sugar’s effect on the body. They found that sugar leads to obesity and several chronic diseases.

Sugar isn’t just less filling. It adds nothing to your diet, other than calories, hence the term “empty calories.”

It’s deceptively bad for you since sugar-sweetened snacks are less filling. You may find yourself munching on a few mini-candy bars when a naturally-sweet banana may have satisfied your hunger. This is possibly due to a sugar-caused hormone suppression that leads to a decrease in satiety, or how full we feel.

And sugar isn’t just less filling. It adds nothing to your diet, other than calories, hence the term “empty calories.” See, there’s a difference between the two kinds of simple sugars. Glucose is the body’s preferred energy source and is found in pretty much any living thing. Fructose is the kind of sugar that’s found naturally in fruits and vegetables, but is also in “added sugar.” It can only be metabolized in the liver and excess energy from fructose is stored as fat.

Sugar is also uniquely tied to insulin- and leptin-resistance, which aid the growth of fat in the body. All these factors combine to create a perfect storm for fat gain. Not weight gain, including muscle or healthy weight, mind you — weight gained through additional body fat.

Why Fat Isn’t Bad for You, but You Think It Is

As we continue to learn about how sugar is bad for a diet, we learn more about how important fat can be. After all, it’s one of the macronutrients for a reason.

The confusion is a result of the easy-to-mix-up kinds of fats. You have the unhealthy, saturated and trans fats, and the healthy, mono-and-polyunsaturated fats along with omega-3 fatty acids. Fairly easy to remember, right? Well, even that simplistic view is no longer accurate.

Even saturated fats are now considered to be healthy in the right amounts. While certain sources of saturated fats are still unhealthy, like processed meats, there are many new diets that are high in fat and still effective. Now, there’s been a massive growth in studies that show that we were simply wrong about fats, and some, like omega-3 fatty acids, are really good for you.

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Again, you shouldn’t eat ALL the fat just because it’s not horrible for you. Overindulging in healthy fats is still overindulging, and you’ll gain weight.

As for sugar, you should be more cognizant of how much you’re taking in and cut back if necessary. You don’t have to cut sugar out entirely, though. What’s important is that you don’t have anything in excess.

No matter what, a balanced diet, mixed with a healthy amount of exercise, is your best bet for keeping your body in tip-top shape. You just have one more option now!

Further Reading

Men’s Health — The Truth About Fat and Sugar is Finally Explained
The New York Times — How the Sugar Industry Shifted Blame to Fat
NPR — 50 Years Ago, Sugar Industry Quietly Paid Scientists to Point Blame At Fat
YouTube — Adam Ruins Everything - Low-Fat Foods Are Making You Fatter | truTV