Obesity is linked to lower levels of testosterone, which in turn induces weight gain. According to earlier research, men aged 45 years or older with low levels of testosterone are about twice as likely to be obese and suffer from type 2 diabetes and high blood pressure as compared with age-matched controls.
Saad and team decided to examine the impact of normalizing blood testosterone levels in predominantly older men with low testosterone levels (hypogonadal) in a cumulative, prospective study.
They analyzed 251 men between the ages of 38 and 83 years, with an average age of 61. The men's baseline testosterone levels ranged from between 0.14 to 3.5 ng/mL, with the cut-off point for testosterone treatment ≤ 3.5. ng/mL (12 nmol/L), a standard cut-off point for testosterone levels to be considered as 'low'. 214 men were followed-up for at least 2 years, whilst 115 were followed-up for at least 5 years. All participants received testosterone undecanoate 1000 mg, with injections given at baseline, after 6 weeks and then every 12 weeks throughout the study period.
Testosterone therapy turned obese men into overweight onesThose followed-up for 5 years lost, on average, 16kg with an average weight drop from 106 kg to 90 kg. The average waist circumference dropped from 107 cm or 42 inches to 98 cm or 38.5 inches, whilst the average body-mass index (BMI) dropped from 34 to 29, meaning that the men dropped from being classed as 'obese', which is a BMI of over 30 to 'overweight', which is a BMI of 25 to 30.
The participants also showed an improvement in other metabolic indicators, such as a drop of LDL or 'bad' cholesterol (mg/dL) from 163 to 109, whilst triglycerides (mg/dL) went down from 276 to 189, and the average blood glucose measurements (mg/dL) fell from 103 to 94. In addition, the participants' systolic blood pressure decreased from 153 to 137 mm Hg and diastolic from 93 to 79 mm Hg.
According to the researchers, there could be various factors responsible for the findings, given that increased testosterone levels improve energy and motivation to perform physical exercise and more movement in general. Testosterone also raises lean body mass, or fat free mass and enhances the patient's energy levels.
The researchers also observed no higher risk of prostate cancer in the participants - their risk of the disease did not rise above the average for other people of their age and general health.
The authors concluded:
"Raising serum testosterone to normal reduced body weight, waist circumference, and blood pressure, and improved metabolic profiles. These improvements were progressive over the full 5 years of the study."
Written by Petra Rattue