Jennifer Lovejoy, Arivale Chief Science Officer, PhD
“Why would anybody think this is a good idea?”
That was the question recently posed by celebrity fitness trainer Jillian Michaels, best known for her role on The Biggest Loser. She was using the results of a new study to make a strong point about how unhealthy the popular low-carb/low-fiber keto diet can be.
It’s well-documented that diets high in complex carbohydrates are associated with beneficial health effects. Specifically, diets high in fiber and whole grains are associated with reduced rates of heart disease, stroke, type 2 diabetes, colorectal and other cancers, and obesity. In addition, dozens of randomized clinical trials show high fiber intake or increased whole grains reduce body weight, improve blood pressure, and reduce blood sugar.
In the recent study published in Lancet this month, researchers performed a series of meta-analyses of 185 prospective studies and 58 clinical trials on dietary fiber and other measures of carbohydrate quality. Researchers looked at total fiber intake, glycemic index or load, and whole grain intake in relation to all-cause and cardiovascular mortality, as well as key health outcomes, such as cardiovascular diseases, type 2 diabetes, stroke, blood pressure, body weight, and multiple cancers.
The study had compelling and – given its size and scope – definitive results. Across the board, higher intakes of fiber or whole grains were associated with reduced all-cause mortality, as well as incidence of multiple chronic diseases and cancers. Fiber intakes of 25-29 grams per day were found to be protective compared to intakes less than 25 grams, with intakes greater than 30 grams per day providing additional benefits.
While we don’t approve of the approach to weight loss taken on The Biggest Loser, in this case we do agree with Jillian Michaels. As she notes, carbohydrates are the main fuel source for our cells, and depriving ourselves of this essential macronutrient is not a good idea.
The popular keto diet is low in healthy whole grains and dietary fiber, which the accumulated evidence shows are key for reducing the risk for many diseases. In addition, both the recent Lancet study and previous studies have shown that diets very low in carbohydrates and high in animal fat and protein, like the keto diet, are associated with reduced longevity. Finally, as noted in the USA Today story about Michaels’ comments, the keto diet is so restrictive that most people who use it for weight loss are unable to stay on it long term and are likely to regain any weight they initially lost.
Our bodies evolved to eat high-quality, complex carbohydrates, which is likely why so many studies show that diets high in fiber and plant foods, including whole grains, are so healthy. If you’re considering the keto diet, look at the evidence around both the sustainability of the plan and the effects of dramatically reducing fiber in your diet. Instead of eliminating all carbs, focus instead on reducing sugar and refined carbs while boosting your fiber intake and you may see both health and weight benefits.
- Everything You Need to Know About the Ketogenic Diet
- The Facts About Carbs – and What To Do When You Crave Them
- The Science and Myths of Fat in Your Diet
[Arivale Hot Topics address health stories currently in the news. The Arivale Clinical Team’s commentary on these news articles is not a review of the scientific evidence, nor an endorsement of a specific study, and is not meant as official medical opinion.]