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Fertility and Weight Loss

Fertility and Weight Loss

Weight loss is about living a healthier, happier life. Why not? Losing those extra fats can indeed improve overall wellness. For many people – both men and women – it is also to increase the chances of getting pregnant. As it turned out, being overweight or obese has a negative implication on fertility. Read on to understand why that is so to have a better understanding of the science.

Infertility in Canada

The widely accepted definition of infertility is failure to conceive after one year or longer of unprotected sex. For women, fertility declines steadily with age. Hence the general recommendation for women 35 years or older is to consult with a reproductive endocrinologist if unable to get pregnant after six months of unprotected sex. Keep in mind, though, that infertility is not exclusive to women but also men.

In Canada, if you were to gather six couples together, there is a chance that one of them may have a fertility issue. 1 in 6 or 16% of couples experience infertility, a number that has doubled since the 80s (“Fertility”).

The cause of infertility in couples by gender are as follows:

  • 30% man
  • 40% woman
  • 20% both man and woman
  • 10% no reason found

There is no denying that infertility can take a toll on relationships, negatively impacting emotional and psychological well-being. The cost of treatments can also place a heavy burden on finances.

Overweight and Obesity in Canada

On weight, healthcare professionals refer to the body mass index (BMI), a calculation based on an individual’s height and body mass.

BMI = weight / height in meter squared

A person with BMI ranging from 18.5 to 24.9 is healthy and most ideal. If it falls between 25 to 29, that person is overweight. At 30 and above, that person is obese.

Overweight and obesity are a long-standing concern in Canada. Consider these figures in 2018 (“Overweight and Obese Adults, 2018”):

  • 8% or 7.3 million Canadian adults (18 years and older) are obese
  • 3% or 9.9 million Canadian adults are overweight

The numbers are staggering. A combined 63.1% of the population are either overweight or obese. Although there is no evidence, perhaps it could be one factor contributing to the continuous decline of the fertility rate in Canada (“Canada Fertility Rate 1950-2020”).

Canada’s fertility rate (births per woman) over the last four years:

  • 2021: 1.500
  • 2020: 1.509
  • 2019: 1.517
  • 2018: 1.525

A fertility rate of 2.1 is a must for the population to stay stable. It has been half a century since Canada met this threshold. At the present course of 1.5, the number of new births is not enough to replace the current population. It is the reason why the government introduced measures to accept 401,000 new permanent residents in 2021.

Fertility and Weight

Discussing the causes of infertility among men and women and treatment options is beyond this article’s scope. In particular, our focus is on weight (body fats) and how it affects fertility.

Infertility in Overweight or Obese Women

Overweight and obese women need more time to conceive. Furthermore, obesity increases the risk of infertility threefold compared to non-obese women (Silvestris et al.). The difficulties in getting pregnant are due to unhealthy weight, causing hormonal imbalances, inability to release an egg from ovaries, and menstrual disorders.

For women seeking assisted reproduction, excess weight negatively impacts intracytoplasmic sperm injection (ICSI), in-vitro fertilization (IVF), and ovulation induction.

Note: Polycystic ovary syndrome (PCOS), which causes low fertility or infertility, is an obesity-related condition.

Infertility in Overweight or Obese Men

Every single-point increase in BMI causes a 2% testosterone decrease (Travison et al.). The waistline is, too, a factor, with every 4-inch increasing the chances of low testosterone level by 75% (Svartberg et al.).

Compared to men with normal BMI, being overweight increases the chances of low sperm count (oligozoospermia) by 11%, no sperm in the ejaculate (azoospermia) by 39%. In obese men, the chances of low sperm count increase by 42%, and no sperm in the ejaculate by 81% (Sermondade). Mainly, this is due to a prime hormonal defect leading to the inability to maintain testosterone concentrations (Katib). Consequently, it negatively impacts the production of sperm.

Erectile dysfunction (ED) is another condition that may arise. For instance, having a BMI of 28 increases the chances of developing this condition by 90% (Garimella et al.).

infertility and weight

Weight Loss and Fertility

There are hundreds of studies on the negative impact of being overweight and obese on health, including fertility. The logical assumption is that for such people to be fertile, they have to lose weight. Indeed, a study shows that much. Losing even only 5% to 10% of body weight can already restore fertility (Balen and Anderson).

Particularly for women, PCOS can be the cause of overweight or obesity. The imbalance in reproductive hormones prevents ovaries from releasing an egg. For women trying to get pregnant, that difficulty does not end there. PCOS also causes insulin resistance that stops ovulation because the ovaries produce less estrogen and more testosterone.

With a BMI of 25 or above, weight loss greatly benefits women’s fertility – and men, too. It is also commonly believed that it helps improve the success rate of fertility treatments. However, recent studies suggest the improvements may not be as significant as previously thought (Gaskins). The focus, therefore, should not merely be about losing weight but also following a healthy diet. It is a must because there is also the entire pregnancy period to consider.


“Fertility.” Government of Canada, 2013,

“Overweight and Obese Adults, 2018.” Statistics Canada, Government of Canada, 25 June 2019,

“Canada Fertility Rate 1950-2020.” Macrotrends,

Silvestris, Erica, et al. “Obesity as Disruptor of the Female Fertility.” Reproductive Biology and Endocrinology, vol. 16, no. 1, 9 Mar. 2018, 10.1186/s12958-018-0336-z.

Travison, Thomas G., et al. “The Relative Contributions of Aging, Health, and Lifestyle Factors to Serum Testosterone Decline in Men.” The Journal of Clinical Endocrinology & Metabolism, vol. 92, no. 2, Feb. 2007, pp. 549–555, 10.1210/jc.2006-1859. Accessed 10 Dec. 2019.

Svartberg, Johan, et al. “Waist Circumference and Testosterone Levels in Community Dwelling Men. The Tromsø Study.” European Journal of Epidemiology, vol. 19, no. 7, July 2003, pp. 657–663,, 10.1023/b:ejep.0000036809.30558.8f. Accessed 2 Nov. 2019.

Sermondade, Nathalie. “Obesity and Increased Risk for Oligozoospermia and Azoospermia.” Archives of Internal Medicine, vol. 172, no. 5, 12 Mar. 2012, p. 440, 10.1001/archinternmed.2011.1382. Accessed 9 Jan. 2021.

Katib, Atif. “Mechanisms Linking Obesity with Male Infertility.” Central European Journal of Urology, vol. 68, no. 1, 2015, 10.5173/ceju.2015.01.435.

Garimella, Pranav S., et al. “The Association between Body Size and Composition and Erectile Dysfunction in Older Men: Osteoporotic Fractures in Men Study.” Journal of the American Geriatrics Society, vol. 61, no. 1, Jan. 2013, pp. 46–54, 10.1111/jgs.12073. Accessed 15 Oct. 2020.

Garimella, Pranav S., et al. “Association between Body Size and Composition and Erectile Dysfunction in Older Men: Osteoporotic Fractures in Men Study.” Journal of the American Geriatrics Society, vol. 61, no. 1, Jan. 2013, pp. 46–54, 10.1111/jgs.12073. Accessed 15 Oct. 2020.

Balen, Adam H., and Richard A. Anderson. “Impact of Obesity on Female Reproductive Health: British Fertility Society, Policy and Practice Guidelines.” Human Fertility, vol. 10, no. 4, Jan. 2007, pp. 195–206, 10.1080/14647270701731290. Accessed 13 Dec. 2019.

Gaskins, Audrey J. “Recent Advances in Understanding the Relationship between Long- and Short-Term Weight Change and Fertility.” F1000Research, vol. 7, 26 Oct. 2018, p. 1702, 10.12688/f1000research.15278.1. Accessed 8 Oct. 2020.


Hormonal Imbalance and Weight Loss

Hormonal Imbalance and Weight Loss

Hormone balancing medications, supplements, diets, and programs are some of the most intriguing weight loss methods. When hormones misfire, the claim is that it leads to uncontrolled weight gain or futile attempts at weight loss. By correcting the hormonal imbalance, you can prevent obesity. More importantly for many people, it aids in getting rid of unwanted fats.


Hormones, secreted by endocrine system glands, act as the body’s chemical messengers. These chemical substances find their way into the bloodstream and get transported all over the body. Upon binding with an organ’s receptors, they send a signal instructing it to function in a specific way. It is in this manner that they play an essential role in controlling and coordinating vital bodily processes, such as:

  • Growth and development
  • Heart rate
  • Body temperature
  • Sleep cycle
  • Reproductive cycle
  • Sexual characteristics
  • Mood
  • Appetite and metabolism

Aside from the processes mentioned above, hormones also play a role in energy use and energy storage in the body. They also regulate the fluids, salts, and glucose (sugar) in the blood.

Hormonal Imbalance and Weight Loss or Gain

The endocrine system secretes more than 50 types of hormones to maintain homeostasis (List of human hormones). Not all of them affect the entire body, as some target only 1 or 2 specific organs. A hormonal imbalance – too little or too much of a hormone – can trigger a severe response even if the change is tiny. The inability to keep bodily functions stable leads to a plethora of conditions, including uncontrolled weight gain or sudden, unexplained weight loss.

Which hormonal imbalances lead to weight gain or weight loss?

1. Insulin

During digestion, carbohydrates from food get converted into glucose. Simultaneously, the pancreas secretes insulin, which triggers glucose and nutrients’ uptake in cells from the bloodstream (expressed as calorie). Once absorbed, glucose becomes energy.

An excessive food intake, particularly high-calorie foods, results in the body producing more calories than needed. Then, the body converts the unused calories into fats, storing them throughout the body, especially in the belly. Failing to live a healthier lifestyle, the accumulation of fats increases weight, which increases the risk of insulin resistance (Kolb et al.).

Over time, the body’s sensitivity to insulin decreases. Consequently, the pancreas secretes higher insulin levels to continue supplying energy to the cells. Without intervention – exercise, better food choices and eating habits – the vicious cycles continue. The body keeps producing higher levels as insulin resistance keeps increasing, leading to diabetes (Olatunbosun and Griffing).

Recently, researchers found a connection between the brain’s sensitivity to insulin, weight, and fat (Kullmann et al.). For one, it determines where the body stores fats.

It also appears that lifestyle intervention for people with high brain sensitivity to insulin can lose more fat and weight. On the contrary,

those with high brain insulin resistance do not lose much weight at all. Furthermore, they regain weight sooner, thus rendering weight loss programs ineffective.

You can look at the relationship between insulin and weight loss as this. It is possible to promote weight loss by controlling – suppressing, or lowering – high insulin levels (Velasquez-Mieyer et al.).

Related article: 4 Ways that Stress Can Affect Your Weight Loss Success

2. Cortisol

The build-up of physical, mental, or emotional stress levels triggers the “flight-of-fight” mode in the nervous system. In turn, the brain responds by signalling the adrenal glands sitting atop the kidneys to secrete cortisol – more popularly known as the stress hormone – as well as adrenaline and noradrenaline.

Think of cortisol as the body’s defence mechanism, a response to perceived or actual threats (Understanding the stress response). It helps heighten your senses and increase energy level by pumping fuel into the bloodstream to run away from danger or fight the stressor. At the same time, it also stops the digestive system and lowers the metabolic rate.

Cortisol and adrenaline produce a burst of energy by breaking down fat. Likewise, these hormones also tap into the carbohydrates stored in the liver and muscles. Instead of losing weight, more people undergoing stress tend to eat more and end up gaining weight (Herhaus et al.). If a high cortisol level contributes to weight gain, low levels may also produce the opposite results – weight loss (Neary and Nieman).

3. Thyroid

Hypothyroidism is an illness caused by an underactive thyroid gland, affecting 2 out of 100 Canadians. A thyroid hormone deficiency primarily slows down the metabolic processes (Hypothyroidism). People suffering from thyroid problems cannot stand cold temperatures, feel tired quickly, gain weight, and more.

The lack of thyroid hormones makes it incredibly challenging to lose weight. However, some medications to normalize its levels appear to help in modest weight loss (Agnihothri et al.).

4. Testosterone

Testosterone hormone in men mainly comes from the testicles and ovaries for women (although at much lower levels). A deficiency may occur with advancing age, leading to late-onset hypogonadism, affecting several organs (Morales et al.). For men, it negatively impacts reproductive and sexual function by causing low sex drive, difficulty with erection, and low semen volume. Because of these, it is – for many – considered as one of the essential sex hormones.

A healthy level of testosterone promotes muscle growth while also suppressing fat gain. As muscles burn more calories than fat tissues, it helps minimize the storage of excess calories as fat. On the other hand, a testosterone deficiency makes it easy for men to gain more weight (Fui et al.).

5. Estrogen

For women, the “dreaded” menopause is when many of them start to gain weight. It is when one estrogen levels drop. In particular, estradiol – a form of estrogen – helps regulate metabolism, keeping body weight in check (Russell et al.). Its decline leads to the accumulation of fat in the abdomen and midsection.

weight loss

6. Leptin

In 1994, scientists made an exciting discovery. Leptin – dubbed obesity hormone, fat hormone, starvation hormone, and hunger hormone – appeared to be a breakthrough treatment for weight loss.

Leptin hormone, produced by fat cells, plays a role in weight management by signalling the brain that there is already enough fat stored. This action curbs appetite to help prevent overeating.

If its level drops, the brain interprets it as starvation, increases appetite, and slowly burns calories (Kelesidis et al.).

An imbalance, particularly leptin resistance, can also occur when the body no longer responds to this hormone. This condition can cause a person to gain weight, and scientists believe it to be a leading cause of obesity (Park and Ahima).

Related article: Why Weight Loss is more than Counting Calories – Part 1: Hormones Play a Role

Hormonal Imbalances and Weight Loss Resistance

Gaining weight due to hormone issues may involve one or more hormones. In some cases, the gain is gradual while sudden in others. Because these chemicals play such an integral role in body processes, other symptoms also occur.

How do most people respond to weight gain?

Unfortunately, many people seek instant gratification by resorting to quick fixes. However, they are not entirely to blame. Makers and sellers of supplements and medication are excellent at creating enticing marketing campaigns. The best way to lose weight, however, is to change lifestyle habits. Exercising, eating healthy food, and getting enough sleep are the preferable ways. As for people who seem to have reached their weight loss plateau and suspect hormones might be the cause, seek help to regain hormone balance.


“List of Human Hormones.” Wikipedia, Wikimedia Foundation, 10 Mar. 2021,

Kolb, Hubert, et al. “Insulin Translates Unfavourable Lifestyle into Obesity.” BMC Medicine, BioMed Central, 13 Dec. 2018,

Olatunbosun, Samuel T. “Insulin Resistance.” Edited by George T Griffing, Medscape, 8 Apr. 2020,

Kullmann, Stephanie, et al. “Brain Insulin Sensitivity Is Linked to Adiposity and Body Fat Distribution.” Nature News, Nature Publishing Group, 15 Apr. 2020,

Velasquez-Mieyer, P A, et al. “Suppression of Insulin Secretion is Associated with Weight Loss and Altered Macronutrient Intake and Preference in a Subset of Obese Adults.” International Journal of Obesity and Related Metabolic Disorders: Journal of the International Association for the Study of Obesity, U.S. National Library of Medicine, Feb. 2003,

“Understanding the Stress Response.” Harvard Health Publishing, Harvard Medical School, 6 July 2020,

Herhaus, Benedict, et al. “High/Low Cortisol Reactivity and Food Intake in People with Obesity and Healthy Weight.” Nature News, Nature Publishing Group, 27 Jan. 2020,

Neary, Nicola, and Lynnette Nieman. “Adrenal Insufficiency: Etiology, Diagnosis and Treatment.” Current Opinion in Endocrinology, Diabetes, and Obesity, U.S. National Library of Medicine, June 2010,

“Hypothyroidism.” Thyroid Foundation of Canada,

Agnihothri, Ritesh V, et al. “Moderate Weight Loss Is Sufficient to Affect Thyroid Hormone Homeostasis and Inhibit Its Peripheral Conversion.” Thyroid: Official Journal of the American Thyroid Association, Mary Ann Liebert, Inc., Jan. 2014,

Morales, Alvaro, et al. “Diagnosis and Management of Testosterone Deficiency Syndrome in Men: Clinical Practice Guideline.” CMAJ, Canadian Medical Association Journal, 8 Dec. 2015,

Fui, Mark Ng Tang, et al. “Lowered Testosterone in Male Obesity: Mechanisms, Morbidity and Management.” Asian Journal of Andrology, Medknow Publications & Media Pvt Ltd, 2014,

Russell, Ashley L, et al. “Dietary Isoflavone-Dependent and Estradiol Replacement Effects on Body Weight in the Ovariectomized (OVX) Rat.” Hormone and Metabolic Research = Hormon- Und Stoffwechselforschung = Hormones Et Metabolisme, U.S. National Library of Medicine, June 2017,

Kelesidis, Theodore, et al. “Narrative Review: the Role of Leptin in Human Physiology: Emerging Clinical Applications.” Annals of Internal Medicine, U.S. National Library of Medicine, 19 Jan. 2010,

Park, Hyeong-Kyu, and Rexford S. Ahima. “Physiology of Leptin: Energy Homeostasis, Neuroendocrine Function and Metabolism.” Metabolism, W.B. Saunders, 15 Aug. 2014,