THE BLOG

Ask JJ: Ketogenic Diets

06/10/2015 01:16 pm ET | Updated Jun 10, 2016

Dear JJ: My adult son has had considerable success doing a ketogenic diet. You mention how healthy carbohydrates are an important part of your diet, yet he seems to thrive on this very low-carb plan.

Ketogenic diets typically restrict carbohydrate to less than 50 grams a day, which means they become higher in protein and especially dietary fat. Generally speaking, ketogenic diets are moderate in protein, high in fat, and very low in carbohydrates.

Especially compared with high-sugar impact or low-fat diets, studies show ketogenic diets yield impressive benefits for weight loss, cardiovascular disease, and Type 2 diabetes. Emerging evidence also suggests benefits for acne, some cancers, and polycystic ovary syndrome (PCOS).

But ketogenic diets err by heavily -- and in my opinion, unnecessarily -- restricting carbohydrates.

In his brilliantly titled blog "Carbs Are Not the Enemy: Oversimplification Is," John Berardi, Ph.D., says reducing healthy carbohydrate intake decreases thyroid function (stalling your metabolism), increases muscle loss, and raises your stress hormones.

"The result? You might find yourself feeling cranky, tired, weaker, or even sick," he writes. "Oh, and your weight loss will probably also stall."

Alan Christianson, N.D., agrees.

"One problem is that when you cut your carbs too much, cortisol rises," he writes in the Adrenal Reset Diet. "This rise in cortisol can turn on the fat-storage enzymes and lead to poorer-quality sleep, both of which work against lasting weight loss."

I've witnessed these and other problems with clients and friends on ketogenic diets who experience fatigue, bad breath, "keto flu," energy crashes, constipation, nausea, and other unpleasant side effects. Never mind having to awkwardly ask your server for a slab of butter to top your sirloin, since ketogenic diets demand very high amounts of fat.

Rather than heavily restrict them, Christianson suggests increasing healthy carbs at dinner. "Like Goldilocks, we need to get them just right: We need the right types of carbs, not too much, not too little, and not too early in the day," he writes.

Smart healthy carbs include legumes, quinoa, spaghetti squash, sweet potatoes, low-sugar impact fruit like berries, and of course, lots of veggies. When you restrict or eliminate these and other plant foods, you miss out on vital nutrients but also meal variety.

While further studies will likely reveal benefits, I've seen too many drawbacks to recommend or sustain a ketogenic diet. While they might work for some people, very-high-fat/super-low carb plans will never become mainstream.

Rather than go to such extremes, why not instead opt for a low-sugar impact diet? Focus your meals on healthy fats like avocado but also lean protein, high-fiber carbs like legumes, and lots of leafy and cruciferous veggies. Eat every four to six hours, starting with a protein shake at breakfast.

Low-sugar impact eating can give you the benefits of a ketogenic diet, including fat loss and stabilized blood sugar, without its drawbacks. That becomes a win-win in my book!

If you've ever done a ketogenic diet, have you experienced any problems I mentioned here? Did you ultimately meet your health goals on a ketogenic diet? Share your thoughts below. And keep those great questions coming at AskJJ@jjvirgin.com.