In this continuation of ‘Are Heavy Metals Making Us Fat? Part 1’, we dive into how heavy metals cause weight gain.

Here are several key mechanisms in which heavy metals affect weight:

1. Heavy Metals Induce Fat Growth

First and foremost, certain heavy metals have been shown to increase fat production in our cells,(1,2) a process termed lipogenesis. Lipogenesis, in a nutshell, takes glucose as fuel and turns it into fat for storage. Evolutionarily-speaking, this helps us maximize periods of food plenty to allow us to survive periods of scarcity. Nowadays, most of us live in a constant state of plenty – this mismatch between our environment and genetic makeup leaves us prone to weight gain.

Insulin is the main driver for lipogenesis, which is why simple carbs and sugars cause weight gain. We now know that heavy metals act in a similar way.

Not only do heavy metals quite literally make us fat, there are other ways in which they cause dysfunction of our adipose tissue. Cadmium, for example, causes abnormal growth, development, and function of fat cells.(3) It also increases blood glucose in the body,(1) contributing to insulin resistance and driving a vicious cycle of insulin dysfunction and weight gain.

2. Heavy Metals Deplete Minerals

The structure of heavy metals is extremely close to that of our nutritive trace minerals such as zinc, copper, iron and magnesium. Because of this, heavy metals are able to kick-out our minerals from their seats in our cells and sit there instead, blocking receptor sites and downstream functions. So even if we are intaking enough of these minerals, heavy metals can create an environment of deficiency.

Deficiency in key essential minerals, particularly chromium, copper, iron, and magnesium are shown to increase weight gain,(4) not to mention, leaving you with little energy for keeping active and maintaining those healthy habits!

3. Heavy Metals Affect Thyroid Function

Our thyroid gland, located at the front of our neck, is the master controller of our metabolism. So much so, unexplained weight fluctuations is the most common early sign of thyroid dysfunction. 

Many research studies have demonstrated the disruptive effects of heavy metals on the thyroid gland. Mercury, a contaminant in much of the world’s seafood, significantly decreases the levels of thyroid hormones (T3 and T4) in our body.(5) Low T3 and T4 is characterized by weight gain, fatigue, hair loss and gut issues. High levels of cadmium, antimony, or tungsten have been linked to more than double the chance of developing thyroid dysfunction!(6) Additionally, many heavy metals such as cadmium, chromium, and lead have been linked to developing thyroid cancer.(7)

4. Heavy Metals Cause Hormone Imbalance

In addition to the thyroid hormones, we have many other hormones that influence how much body fat is stored, where it is stored, and how we access it for energy. Estrogen and cortisol are two of the most important hormones for weight regulation. While high estrogen can promote weight in our hips, thighs and breasts, cortisol can increase belly fat.

Many toxins are endocrine disruptors, meaning they interfere with our normal hormone functions. They can 1) mimic or inhibit the actions of a hormone by interacting with its receptor or mechanism of action, 2) alter the synthesis of the hormone or its receptor, or 3) alter the rate of metabolism or excretion of the hormone.(8)

For example, heavy metals like cadmium, lead, arsenic, and mercury mimic estrogen in the body (thus termed ‘xenoestrogens‘) and have been linked to breast cancer, early puberty onset, and fertility issues.(9) At the same time, studies have noted that cortisol levels are so sensitive to heavy metal exposure that cortisol should be considered as a potential testing biomarker.(10) This disruption of cortisol has also been shown to pass from mother to fetus during pregnancy.(11)

To sum it all up!

While exercise, a healthy diet, and a positive lifestyle are always the pillars for weight management, it is worthwhile to acknowledge that environmental toxins and chemicals like heavy metals may be playing a role in your weight struggles. If you think heavy metals may be contributing to weight, or other sub-optimal health symptoms, we recommend a heavy metal and mineral analysis to understand your toxicity levels and take the necessary steps to clear out toxins for long-term health and well-being.

References:

1. Skolarczyk J., Pekar J., Łabądź D., Skórzyńska-Dziduszko K. 2018. Role of heavy metals in the development of obesity: A review of research. J. Elem., 23(4): 1271-1280. DOI: 10.5601/jelem.2018.23.1.1545
2. Mailloux R, Lemire J, Appanna V. Aluminum-induced mitochondrial dysfunction leads to lipid accumulation in human hepatocytes: a link to obesity. Cell Physiol Biochem. 2007;20(5):627-638. doi:10.1159/000107546
3. Kawakami T, Sugimoto H, Furuichi R, Kadota Y, Inoue M, Setsu K, Suzuki S, Sato M. (2010). Cadmium reduces adipocyte size and expression levels of adiponectin and Peg1/Mest in adipose tissue. Toxicology, 267(1-3): 20-26.
4. Kawakami T, Sugimoto H, Furuichi R, et al. Cadmium reduces adipocyte size and expression levels of adiponectin and Peg1/Mest in adipose tissue. Toxicology. 2010;267(1-3):20-26. doi:10.1016/j.tox.2009.07.022
5. Chen A, Kim SS, Chung E, Dietrich KN. Thyroid hormones in relation to lead, mercury, and cadmium exposure in the National Health and Nutrition Examination Survey, 2007-2008. Environ Health Perspect. 2013;121(2):181-186. doi:10.1289/ehp.1205239
6. Liao X. “Exposure To Heavy Metals In Relation To Thyroid Dysfunctions In U.S. Adults” (2019). Public Health Theses. 1833. https://elischolar.library.yale.edu/ysphtdl/1833
7. Rezaei, M., Javadmoosavi, S.Y., Mansouri, B. et al. Thyroid dysfunction: how concentration of toxic and essential elements contribute to risk of hypothyroidism, hyperthyroidism, and thyroid cancer . Environ Sci Pollut Res 26, 35787–35796 (2019). https://doi.org/10.1007/s11356-019-06632-7
8. David O. Norris, Endocrine Disruptors of the Stress Axis in Natural Populations: How Can We Tell?, American Zoologist, Volume 40, Issue 3, June 2000, Pages 393–401, https://doi.org/10.1093/icb/40.3.393
9. Georgescu, Bogdan & Georgescu, Carmen & Dărăban, Stelian & Anca, Boaru & Paşcalău, Simona. (2011). Heavy Metals Acting as Endocrine Disrupters. Anim. Sci. Biotechnol. 44.
10. Pérez-Cadahía B, Laffon B, Porta M, et al. Relationship between blood concentrations of heavy metals and cytogenetic and endocrine parameters among subjects involved in cleaning coastal areas affected by the ‘Prestige’ tanker oil spill. Chemosphere. 2008;71(3):447-455. doi:10.1016/j.chemosphere.2007.10.053
11. Sobolewski M, Conrad K, Marvin E, Allen JL, Cory-Slechta DA. Endocrine active metals, prenatal stress and enhanced neurobehavioral disruption. Horm Behav. 2018;101:36-49. doi:10.1016/j.yhbeh.2018.01.004

Rachel Erwin, Nutritionist & Content Writer

Rachel is a Nutritionist with a BSc in Biology and Global Health from the University of Toronto, and a Postgraduate Diploma in Human Nutrition from the University of Ulster. She has counselled and educated clients in Hong Kong, whose health goals ranged from weight loss to detox and hormone balancing. Her love of writing led her to complete ‘Writing in the Sciences’, offered by Stanford University, and since then she has contributed several evidence-based health articles to various publications.