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Can eating fat help you lose weight? Let’s look at the ketogenic diet.


Fat makes your meals more palatable and helps you feel full, so it’s no wonder the high-fat ketogenic diet is increasing in popularity. The diet has been trending for the past three years, as “keto” blogs and cookbooks continue to pop up and build an impressive fan base. This diet has been used under close supervision by physicians and dietitians since the 1920s for treating epilepsy and has shown promise in managing brain cancer. But is it useful and healthy as a strategy for weight loss?

First, the basics: On the ketogenic diet, at least 70 percent of your daily calories come from fat. Five to 10 percent of your calories come from carbohydrates (20 to 50 grams a day). The rest, up to 25 percent of your daily energy, comes from protein. By contrast, the healthy diet recommended by the Institute of Medicine is 45 to 65 percent carbs, 20 to 35 percent fat and 10 to 35 percent protein.

The ketogenic diet’s low-carb target can be met only by avoiding grains, dairy products, fruit, and legumes such as chickpeas and lentils. Starchy vegetables such as sweet potatoes and squash are out, and even amounts of lower-carb vegetables are limited.

So what’s left to eat? Typically, eggs cooked in butter for breakfast; for lunch and dinner, meat, chicken or fish with salad or green vegetables and plenty of oily dressing. Sorry folks, no alcohol on this diet. Even red wine is out.

[To get a flatter belly, start by getting enough sleep]

The ketogenic diet gets its name from a process called ketosis. Ketosis happens when your body doesn’t have enough energy from glucose (carbohydrates), so it adapts by using stored fat for energy. The result? Weight loss.

Does the ketogenic diet lead to faster or more sustainable weight loss than other diets? The research to date suggests that initial weight loss on the keto diet is impressive but that people aren’t able to stick to the regime for long.

One study, for example, compared the impact of a ketogenic diet (where participants ate less than 20 grams of carbohydrates a day) to a low-glycemic-index diet (where participants reduced their caloric intake by 500 a day) on weight loss in 49 obese individuals with Type 2 diabetes. After six months, the group on the keto diet lost an average of 24.5 pounds, while the low-glycemic-index group lost 15.2 pounds.

But a recent meta-analysis combining the results of 13 randomized-control trials (1,415 participants) of a year or longer found that people on a ketogenic diet lost an average of two pounds more after a year and improved their triglycerides, high-density lipoprotein (HDL) cholesterol and blood pressure compared to those on a low-fat diet. However, when the researchers looked at studies that followed participants for two years, they found that HDL improved more in the keto diet group but that there was no difference in weight loss between the groups.

While the ketogenic diet is promoted as key to switching your body into fat-burning mode, research suggests that fat loss actually slows down as your body starts to break down your muscle for energy.

Pros of the ketogenic diet

1. You don’t need to count calories.

Instead of worrying about calories and portion sizes, some people find it e