By Dr Ananya Mandal, MD
Obesity is one of the major health challenges worldwide, especially the developed nations. Obesity is a major cause of ill health and premature death in countries leading to an increase in the risk of heart disease, diabetes, hypertension, stroke, osteoarthritis and some cancers like colon and breast.
Definition of obesity
Individuals are considered obese when they weigh more than 20% above their ideal weight. Body Mass Index (BMI) is calculated as weight in kilograms divided by height in meters squared.
The currently accepted criteria for overweight is defined as BMI levels greater than 25 kg/m2 and obesity as BMI of 30 kg/m2.
Prevalence of obesity
The current prevalence of obesity in the UK is around 20% whereas in the United States nearly 34% of the population is overweight or obese.
These rates are rapidly increasing in both countries. In UK for example, 2010 estimates suggest that in the absence of substantial intervention, obesity rates would rise to around 50% in the adult population by 2050 increasing annual NHS costs of obesity to £10 billion and societal costs to £49 billion by 2050.
Obesity and sexual health
Apart from other areas of health, another major ailment associated with obesity is poor sexual health. Obesity results in infertility and difficulty in conception among women.
Obesity and onset of puberty
Studies have shown that obesity may have an effect on the onset of pubertal changes. Obesity in teenagers advances puberty in girls while it delays puberty in boys. The key reasons behind this could be leptin and insulin alterations in the obese child.
Obesity and male sexual health
Obese men tend to have lower total and free testosterone levels. Testosterone is the major male hormone. Testosterone results in deep voice, large muscles, development of male sexual organs and strong bones. Testosterone is also responsible for sperm production and libido in men.
The hormone gets converted to dihydrotestosterone and then helps growth of the prostate. Testosterone levels begin to rise at puberty and peak in early adulthood after reaching a plateau and then declining with age.
Obesity tends to reduce the levels of testosterone. Studies have shown that in men over 40 each one-point increase in body mass index (BMI) was associated with a 2% decrease in testosterone.
In addition a four-inch increase in waist size increased a 30 years and above aged man’s risk of having a low testosterone level by 75%.
An Australian study reveals that one in every seven obese men could benefit from testosterone replacement. This rate is more than four times higher than in normal weight men.
Obesity and erectile dysfunction
Hormonal disorders and low testosterone levels are responsible for only 3% of cases of erectile dysfunction. But even with normal testosterone levels, obese men have an increased risk of erectile dysfunction.
Studies have linked abdominal obesity to erectile dysfunction especially in older men. They suggest that having a BMI of 28 increased a man's risks of developing erectile dysfunction by 90%.
Losing weight on the other hand is linked to improvement in symptoms. Obesity in men is also directly linked to low frequency of sexual intercourse.
Obesity and reproductive functions
Obesity is definitively liked to low sperm counts and reduced sperm motility in many studies. This leads to male infertility due to obesity. Studies have shown that for every three-point increase in a man’s BMI, couples were 10% more likely to be infertile.
Furthermore, higher temperatures of the testes are linked to low sperm count. Excess fat in the inner thighs and pubic region results in high testes temperatures of over 35˚C. This may be sufficient to hinder sperm production.
Obesity and Benign prostatic hyperplasia or enlargement of prostate
Obesity is linked to a benign enlargement of prostate common in older men. Men with waists of 43 inches or larger have been found to be 2.4 times more likely to need surgery for Benign prostate hyperplasia than men with waists smaller than 35 inches.
Prostate gland also releases prostate-specific antigen (PSA). The PSA levels rise as the prostate gland enlarges. Obesity however lowers PSA. According to the 2001–2004 National Health and Nutrition Examination Survey of Caucasian men ages 40 and older, each five-inch increase in waist circumference results in a 6.6% decline in blood PSA levels. This result could be not due to low production of PSA but due to dilution of blood in obese individuals.
PSA is a measure for progression of prostate cancer. Studies have linked extra body fat and risk of developing prostate cancer. According to the American Cancer Society being overweight increases a man's risk of prostate cancer by 8%, being obese raises the risk by 20%, and being severely obese increases risk by 34%. In addition obesity causes recurrence of prostate cancer and also raises the risk of its spread to other organs.
Reviewed by April Cashin-Garbutt, BA Hons (Cantab)
Last Updated: Apr 8, 2013