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  • Writer's pictureJulia Ryan

Keto and Paleo: Fad Diets or Healthy? | Nutrition Mythbusters

Balanced is excited to bring to you our Nutrition Mythbusters series in which we debunk eight major myths about the links between diet and health! We believe that accurate, evidence-based nutrition information should be accessible to everyone. That’s why we created this educational series dispelling some of the most common and persistent misconceptions regarding healthy, balanced eating and diet-related disease. You can find the video episode of today's blog on our YouTube channel.


Hallmarks of fad diets include unrealistic claims and questionable science. Fad diets sometimes remove one or more food groups entirely. As a result, those following fad diets run the risk of virtually eliminating essential vitamins and minerals.

Carbohydrates have been frequently targeted of late and are the subject of a commonly circulating myth: that restricting carbohydrates and increasing protein and/or fat in the diet is the healthiest diet, especially for weight loss and reversing disease. This is patently false.

Typically, a low-carbohydrate diet is considered to be 50 grams or less of carbohydrates a day. Just one banana has about 27 grams of carbohydrates. This means daily energy intake is derived almost entirely from fat and protein sources. In contrast, a low-fat diet means about 10-15% of daily energy intake is derived from fat.

One of the most notable low-carbohydrate diets is the “ketogenic” (a.k.a. keto) diet. About 80-90% of calories are derived from fat, such as from meat and eggs. The paleo diet, another popular low-carb diet, eliminates legumes, grains and dairy.

It is important to recognize and examine the history of the dietary patterns in focus.

The paleo diet is based on the notion that we should be consuming a diet in line with what “cavemen” ate. Meanwhile, the keto diet was originally designed to assist patients with severe epilepsy, particularly infants and young children and is not a recommended diet for the general public. The diet has now become popular for its perceived prowess in achieving “ketosis,” a metabolic process that uses fat as the only energy source. To put it simply, inadequate carbohydrate consumption results in very low glucose levels, the body’s preferred source of energy. The thought process is that fat-burning ketosis will result in sustained weight maintenance and good health.

However, ketosis is extremely difficult, if not impossible, for adults to achieve. In addition, ketogenic diets do not have a “metabolic advantage” over high-carbohydrate diets as their proponents claim. The keto diet actually does a poor job of maintaining optimal systemic health, such as through lowering blood pressure and stabilizing blood sugar. Instead, a high-fat diet actually contributes to systemic inflammation and the onset of insulin resistance, which in turn precedes type 2 diabetes.

The rise in “popularity” of paleo and keto diets is due, in part, to favorable coverage in popular media and celebrity endorsements, not evidence-based science.

Despite claims to the contrary, the keto and paleo diets rank near the bottom in terms of “heart-healthy” diets.

A U.S. News & World Report analysis led by nutrition experts ranked keto and paleo diets 31st out of 35 diets evaluated for health. Overall, keto was ranked poorly in every category outside of short-term weight loss.

High-fat diets are, as the definition suggests, rife with dangerous fats. Saturated and trans fats, in particular, contribute to high cholesterol levels. As such, the keto diet promotes diet-related diseases such as type 2 diabetes and cardiovascular disease.

In addition, high-fat diets are deficient in fiber. A low fiber intake can contribute to irregular blood sugar, constipation, and increased risk of chronic, diet-related diseases. Fiber also improves satiety, the feeling of fullness, which can prevent overconsumption.

Now that we’ve debunked the presumed efficacy of high-fat diets, here is the fact: a diet rich in plant-based foods and low in animal-source fats is best for health. This dietary pattern assists with disease prevention and weight maintenance, unlike high-fat diets centered on animal proteins.

As mentioned, high-fat diets contain unhealthy levels of saturated fats. There are benefits to replacing saturated fats with polyunsaturated fats. They include anti-inflammatory properties and a reduced risk of type 2 diabetes. Nuts and seeds are popular sources of polyunsaturated fat.

In terms of weight maintenance, one experiences greater long-term success when following a high-carbohydrate diet. In fact, there is an ~80% greater body fat loss when calories from fat are cut rather than calories from carbohydrate foods. Of course, carbohydrates are best consumed in the form of fiber-rich, nutrient-dense foods like 100% whole grains, legumes, fruits, and vegetables; reserve the highly processed and sugary foods as occasional treats.


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