Are low carb diets good or bad for your thyroid? It’s certainly a controversial issue with many well respected practitioners and nutritionists not always agreeing. Some claim that low carb is the holy graille of weight loss and the path to optimal health, while others condemn the diet for wrecking their thyroid and causing hormonal chaos. Who is right? The issue is a nuanced one with a few factors at play.
What does the scientific data tell us?
Very low carb diets like the ketogenic diet (usually under 50 grams of carbs per day), has been shown to slow thyroid function in both children and adults. The findings indicated that the lower the diet was in carbs, the more T3 hormone levels were lowered. T3 is the active thyroid hormone that the body can use. When levels are too low (as in the case of classic hypothyroidism or “sluggish thyroid”) one can feel tired, depressed, cold and more easily gain weight.