Hypothyroid Diets: Why Patients with Hypothyroid Problems Might Gain Weight, and What This Might Tell Us about Obesity

Hypothyroid diets are often counseled for patients who suffer from hypothyroidism. Unfortunately, weight gain is a common side effect. What might this tell us about how extra calories get stored as fat?The Caloric Balance Hypothesis suggests that one can put on weight only by establishing a positive caloric balance: by overeating calories and/or by failing to burn them off. Thus, for hypothyroidism to cause weight gain, the condition must induce appetite and/or impair the body's ability to burn calories.

The Lipophilia Hypothesis tells us that weight gain can and will occur when hormonal and other endocrinological factors change the disposition of the fat tissue itself, most likely by doing something to change insulin levels or insulin sensitivity. So hypothyroidism changes weight by changing the fat tissue.

How can we resolve which hypothesis best explains our dilemma about hypothyroid diets? If we can find evidence that points to a connection between hypothyroidism and insulin resistance or hyperinsulinemia, that would seem to support Lipophilia.

Let's look at some randomly selected scientific articles:

1. Here is an article: "Acanthosis nigricans, hypothyroidism, and insulin resistance."[1]

The authors discuss a skin condition as well as hypothyroidism and note that both associate with insulin resistance. 2. Here is another article that has relevance to our discussion about hypothyroid diets: "Subclinical hypothyroidism is associated with insulin resistance in rheumatoid arthritis."[2]

The authors found that:

"Subclinical hypothyroidism was commonly encountered and associated with insulin resistance and its related dyslipidemia... [They also found that] after controlling for potential confounding variables, subclinical hypothyroidism remained independently predictive of the homeostasis models has been for insulin resistance."

3. Here is an article that reinforces the point that hypothyroidism does indeed associate with overweight: "Weight gain following treatment of hyperthyroidism."[3]

The researchers found that "patients who became hypothyroid... gained most weight."

4. Here is another intriguing article: "Long term weight regulation in treated hyperthyroid and hypothyroid subjects."[4]

Researchers found that:

"Hypothyroid subjects have a small decline in mean body weight over the first six months of treatment they will return to pretreatment weight by 24 months. In the absence of significant metabolic arrangement, body weight is regulated within narrow limits over many years. Effective treatment of hypothyroidism is accompanied by weight gain."
Consider again this key sentence: "Body weight is regulated within narrow limits over many years."

The Caloric Balance Hypothesis leaves no room for physiological factors to "regulate" our weight – unless they act specifically on "Calories In" or "Calories Out." And as we have discussed at length, the fact that we maintain our body weight constantly over time creates another challenge to the prevailing wisdom.

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1. Matsuoka LY, Wortsman J, Gavin JR 3rd, Kupchella CE, Dietrich JG. "Acanthosis nigricans, hypothyroidism, and insulin resistance." Am J Med. 1986 Jul;81(1):58-62.

2. Dessein PH, Joffe BI, Stanwix AE. "Subclinical hypothyroidism is associated with insulin resistance in rheumatoid arthritis." Thyroid. 2004 Jun;14(6):443-6.

3. Dale J, Daykin J, Holder R, Sheppard MC, Franklyn JA. "Weight gain following treatment of hyperthyroidism." Clin Endocrinol (Oxf). 2001 Aug;55(2):233-9.

4. B. Hoogwerf, F. Nuttall. "Long term weight regulation in treated hyperthyroid and hypothyroid subjects." The American Journal of Medicine, Volume 76, Issue 6, Pages 963-970.

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