By Dr. Sarah Zadek ND
The inability to
lose weight from diet and exercise alone can be extremely frustrating. There
are many factors that affect weight management, and for those who struggle with
this it may be worth investigating other causes of this “stubborn metabolism.” One
such cause is the functioning of the thyroid gland and its respective hormones.
Thyroid hormones play crucial roles in how the body uses energy and regulates
appetite. Additionally, fat cells, also called adipose tissue, contains their
own messengers and hormones that affect energy stores and usage. The interaction
between these cells, their messengers and thyroid hormones are major factors
that contribute to weight management.
act directly and indirectly on metabolic cycles. As such, they help decide how
and when cellular energy is used. Because of this relationship, it’s been
theorized that there is a direct relationship between obesity and thyroid function.
An overactive thyroid, hyperthyroidism,
often results in weight loss, whereas an under-functioning thyroid and low
levels of thyroid hormone (hypothyroidism),
can lead to weight gain and/or an inability to lose weight.
What are thyroid hormones?
Your doctor may
have told you that your “thyroid levels” are too high and they want to
prescribe a thyroid hormone. Your doc is referring to your “TSH” – your thyroid
stimulating hormone level. This is a hormone that tells your thyroid gland to
produce and secrete a thyroid hormone called thyroxine. Thyroxine (also
referred to as T4) turns into the active form of thyroid hormone referred to as
T3. When TSH levels are found too high it means that your body is sending out a
signal to the thyroid gland and the signal is not registering. The brain keeps
sending out more signal waiting for a response, but without a response, more
TSH is sent out, resulting in higher than normal levels. When this happens,
your doctor will often prescribe T4 in a form called levothyroxine.
T3 hormone, temperature and metabolism
One of the roles
of the active thyroid hormone T3 is to control our basal metabolic rate by
exerting heat-generating activity. This explains why one of the symptoms of
hypothyroidism is feeling cold. In one animal study, mice without thyroid
receptors had lower metabolic rates, body temperature and were more intolerant
to cold temperatures.
The link between
T3 and metabolism has been investigated for decades. We’ve found that when lean
individuals overeat, the rate of T3 production significantly increases.
However, when calories are restricted in both lean and obese subjects
researchers have reported that T3 decreases, which will slow down metabolism in
the long run.
So why can’t we
just take T3 for weight loss? Because it doesn’t always work, especially in
patients who have normal thyroid levels. A meta-analysis reported that although
patients given T3 had reduced levels of TSH, only 20% of patients actually had
significant weight loss. The thyroid is not the only regulating hormone here.
Thyroid and fat tissue
Leptin is a
hormone found in adipose (fat) cells and is another controlling factor in
weight management. Leptin helps control food intake and energy expenditure. In
general, adipose tissue increases leptin levels, which then increases TSH.
As of 2014, 18
studies have shown a positive correlation between adiposity and TSH levels. However,
it should be noted that these studies looked at correlations, and that other
factors such as insulin sensitivity and diet weren’t always taken into consideration.
What’s important to note is that although it’s been confirmed that a
high-normal TSH level is associated with a high body-mass index (BMI), it’s not
clear whether the increased TSH levels are a consequence of being overweight or
if it causes increased body weight.
Natural treatments for thyroid-related weight
The herb Coleus forskohlii has demonstrated the
ability to increase the production and release of thyroid hormones. Several studies
have reported the potential of the herb C.
forskohlli to help with weight management. One study found that treatment,
combined with a hypocaloric diet, led to significantly reduced hip and waist
circumference, an increase in HDL cholesterol (the “good”
cholesterol), and improvements in insulin resistance.
treatment is the combination of zinc and selenium. Both are important elements
involved in the metabolism of thyroid hormones. One study looked at the effect
that supplementation with zinc and selenium had on thyroid function in
overweight women with hypothyroidism. Women who were given zinc and selenium
together, or zinc on its own both had significantly increased levels of the active
hormone. The zinc and selenium treatment also led to significantly lower TSH
and sluggish thyroid function (elevated TSH levels) are associated with weight
gain. The continuous interaction between the thyroid gland and fat tissue help
to control energy stores and usage. Changes in thyroid functioning can affect
this dynamic, though there are many factors involved in weight management.
Dietary changes should be incorporated into any treatment plan. Other
considerations include herbs such as Coleus
forskohlli and elements such as zinc and selenium.
Thyro-weight: unlocking the link between thyroid disorders and weight. J Assoc
Physicians India. 2018; 66(3): 75-8
Loftus HL, et al.
Coleus forskohlii extract supplementation in conjunction with a hypo caloric
diet reduces the risk factors of metabolic syndrome in overweight and obese
subjects: a randomized controlled trial. Nutrients. 2015; 7(11): 9508-22
et al. Effects of zinc and selenium supplementation on thyroid function in
overweight and obese hypothyroid female patients: a randomized double-blind
Santini F, et al.
Mechanisms in endocrinology: the crosstalk between thyroid gland and adipose
tissue: signal integration in health and disease. Eur J Endocrinol. 2014;