Can Sugar Make You Fat?

Susan McQuillan

Reviewed by QualityHealth's Medical Advisory Board

When you are overweight, you are actually over-fat—you weigh too much because there’s too much fat in your body. That body fat can easily come from an excess of fat in your diet, but it can also come from too much sugar.

Sugar in Your Diet

Sugar is a form of carbohydrate, a major source of fuel for the body. Sugar is found naturally in foods such as fruit and dairy products. Many foods with naturally-occurring sugars are part of a healthy and balanced diet; it’s foods with added sugars that cause the greatest concern. For most people, added sugar in the diet comes from foods and drinks like cakes, cookies, and other baked goods; carbonated sodas; candy; canned fruit, and sometimes otherwise healthy foods, like fruit-flavored yogurts. Then there’s the sugar (and other caloric sweeteners, including honey and maple syrup) you sprinkle into coffee, tea, breakfast cereals, and other foods. Limiting your intake of foods with added sugar can help you avoid consuming too much sugar.

Sugar and Disease

You probably associate excess sugar in your diet with an increased risk of high blood sugar, diabetes, or cavities. But in fact sugar is just as closely connected with higher levels of fats in the blood (triglycerides). Triglycerides come from fat in your diet, but your body also makes them from the excess carbohydrates (sugars) you’ve consumed. Triglycerides can be used for energy or stored for future use. That stored fat is what you see hanging from your belly, back, and thighs.

How it Works

Once carbohydrates from the foods you eat are digested and broken down in your stomach, they are further broken down to glucose (a simple sugar) in your small intestine. From your intestine, glucose is absorbed into your bloodstream, where it travels to individual cells throughout the body, to be used immediately for energy and other purposes. Your liver converts excess glucose to glycogen, which is the body’s stored form of sugar. If there is more glucose than your liver can convert, that excess glucose travels to fatty tissue, where it is turned into triglycerides and stored in your body as fat.

Hurting Your Heart

In addition to causing weight gain, excess sugar in the diet that results in high triglyceride levels puts both men and women at risk of developing heart disease: High triglycerides are often accompanied by high total cholesterol and LDL (bad) cholesterol, and low HDL (good) cholesterol. Even if you don’t have high cholesterol, high triglycerides are considered a risk factor for cardiovascular disease, especially for women. For this reason, the American Heart Association recommends a daily limit on added sugar—two tablespoons (six teaspoons) for women, and three tablespoons (9 teaspoons) for men.

A Note on Protein

Unlike carbohydrates, protein is not converted to fat. Instead, it’s broken down into amino acids, which are used to make enzymes and support muscles and other body tissues. It is almost impossible to get fat from eating too much protein, "But don’t be tricked into thinking your body uses excess protein to build more fat-burning muscle tissue," warns registered dietitian Alison Massey, director of Diabetes Education at The Center for Endocrinology at Mercy Medical Center in Baltimore. "Extra protein is simply stored until it is needed for other jobs."

Very few foods are pure protein, anyway; most contain a mix of protein, carbs, and fat. So eating too much of any type of food can lead to an excess of calories that ultimately end up as body fat.

The Bottom Line

Whether your body fat comes from carbohydrates or directly from dietary fat, the problem is cumulative: The more food you eat, the more calories you’ll take in and, unless you are burning off the excess by getting enough exercise, you will gain more and more weight as time goes by.

The solution for most people is balance: balancing your diet with a variety of different types of foods, and balancing the amount of food you eat with enough exercise to help keep that food from turning into fat.

Alison Massey, MS, RD, LDN, CDE, reviewed this article.