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Why you should avoid the keto diet during pregnancy

The ketogenic, or keto, diet is low-carb, high-fat and moderate-protein diet and popular weight loss method. In a traditional keto diet, you eat less than 50 g of carbs per day (for reference, a medium apple has about 25 g of carbohydrates). The keto diet has been shown to help non-pregnant people lose weight and, if done healthfully, may help reduce the risk of Type 2 diabetes and assist with blood sugar control for patients with Type 2 diabetes. (Note: It’s always best to check with your doctor before starting a new diet or eating plan.)

The theory is this: if you restrict carbs, your body produces ketones, by-products of fat breakdown that are used as energy when there’s no glucose around. That said, the people who see the best results from the keto diet are also choosing healthy fats and protein sources.

Perhaps you’re wondering if the keto diet is a healthy way to eat during pregnancy, especially if there’s a risk or diagnosis of gestational diabetes. Or you may already be on the keto diet, and since gotten pregnant. Dr. Lorraine Lipscombe, an endocrinologist and director of the division of endocrinology at Women’s College Hospital, does not recommend restricting carbs during pregnancy, even if you have gestational diabetes. “When you restrict carbs too much, your body produces ketones, which can be harmful to a developing fetus,” says Dr. Lipscombe. “We don’t recommend restricting carbs during pregnancy, but working with a registered dietitian to come up with an eating plan that makes sense for you.” The key is to remember that there are good carbohydrates and not-great carbohydrates like white bread, pasta, fruit juice and soda. The good ones (berries, beans, lentils, barley, sweet potatoes, squash, yogurt and cheese) offer essential nutrients necessary for the healthy development of your fetus. Servings of these foods should be spread out over the day into three meals and snacks as needed. You can definitely maintain a stable blood sugar without going into ketosis. 

THE EXPERT Dr. Lorraine Lipscombe, endocrinologist and director of the division of endocrinology, Women’s College Hospital.

This information is provided by Women's College Hospital and is not intended to replace the medical advice of your doctor or healthcare provider. Please consult your healthcare provider for advice about a specific medical condition. This document was last reviewed on November 25, 2019.

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