In recent years the number of health advocates promoting low carbohydrate and ketogenic diets have exploded, offering simple ways to lose weight, reduce inflammation, and control blood sugar. But are low carb and keto diets good for people who have a thyroid condition like Hypothyroidism or Hashimoto’s? The short answer is no, but let’s look at why this is.

For a long time, we were told that carbs were good and to avoid saturated fat as this lead to disease. But as saturated fat consumption went down and chronic disease rates skyrocketed, it became clear that the science on this was wrong and consumption of the right fats was actually good for you, and perhaps the over consumption of carbs, especially sugar was more of an issue. While there is a large degree of truth in this, the current trend of cutting almost all carbs from the diet is presenting a new set of problems.

Drastically reducing carbs has been shown to be an effective way to control weight, blood sugar, and help reduce the symptoms of some disease. When carbs are reduced to such a level that the body must find another energy source, this is called ketosis – where the liver converts fat to ketones, and this in turn is used by the body and especially brain as an alternative source of energy.

Getting the body to switch fuel sources in this way has shown great results in the control of epilepsy, and certain other diseases. The other added benefit- weight loss. Sounds great right? Well not so fast. Even though the body can and will use fat as a primary energy source, it only does so when carbohydrates are not available – your body prefers carbs as a fuel source over fat. When adequate carbs are not available, this creates a mini crisis in the body which stresses the adrenals, and down regulates the thyroid which in turn produces fewer thyroid hormones.

“Your body prefers carbs as a fuel source over fat. When adequate carbs are not available, this creates a mini crisis in the body which stresses the adrenals, and down regulates the thyroid which in turn produces fewer thyroid hormones.”

The thyroid is responsible for hormone production and regulation, it affects your mood, your body temperature, and plays an important role in metabolism and reproductive health. As many of us know, a poor functioning thyroid can affect just about every aspect of your health and life. In order for the thyroid to function correctly, and especially convert T4 into T3, it requires glucose, but when this is limited by a low carb or ketogenic diet, the thyroid in turn will produce less thyroid hormones and can potentially increase the level of Reverse T3, exacerbating any existing thyroid condition.

So, if someone already is suffering from low thyroid hormone or their thyroid is being attacked by thyroid antibodies as is the case in Hashimoto’s, drastically reducing carbs is not a great idea and could lead to bigger problems down the road.

Simply put:

  • Carbohydrates are converted into glucose which in turn is used for energy by the body
  • The thyroid needs glucose to function properly and produce hormones
  • Very low carb, or ketogenic diets can negatively affect thyroid function and stress adrenals

In conclusion, although very low carb and ketogenic diets can be an effective way of controlling some diseases, and can provide benefits in certain circumstances, they are not suitable for everyone, especially those who have already have issues with their thyroid or adrenal glands.