28 May Testosterone Treatment Linked to Weight Loss in Obese Men
MedicalResearch: What are the main findings of the study?
Dr. Saad: There are two ongoing registry studies in men with testosterone deficiency (hypogonadism, defined by two separate measures of low serum testosterone and the presence of symptoms which are typical for testosterone deficiency). The studies are being conducted by office urologists. The total number of men who have been treated for a maximum duration of six years is 561, mean age just under 60 years. All men received three-monthly intra-muscular injections of a long-acting testosterone depot preparation.
The main findings were that at baseline only five per cent of these men had normal weight, some 25 per cent were overweight and the majority obese. Both overweight and obese men showed reductions in weight and waist circumference. The more obese men were, the more they lost. Men in the highest obesity category grade III (BMI ≥ 40 kg/m2), had a mean weight loss of 26 kg and a reduction of waist size by 12 cm.
In parallel, all components of the metabolic syndrome improved in a clinically meaningful magnitude, i.e., blood pressure, lipid profile, and glycemic control. When we analyzed a subgroup of 156 men with type 2 diabetes, we found marked improvements in their diabetes as a result of adding testosterone to the standard diabetes treatment men are receiving by their famaily physicians.
MedicalResearch: Were any of the findings unexpected?
Dr. Saad: Initially, this came as a major surprise. When we first analyzed our data after a maximum treatment duration of four years, we were genuinely surprised by the consistent weight loss which had not been described before for testosterone treatment. After six years, the data have been confirmed. There are also data by other groups, for instance, a small but controlled study by Prof. Aversa from Rome.
The results were surprising because they had been unexpected and unintended. Patients had not received any instructions for lifestyle changes, other than the well-meant advice to eat healthier and move more (take the bicycle instead of the car). As we all know, this advice usually has very little and short-lived impact if any. The study is about long-term efficacy and safety of testosterone treatment and purely observational. It is by no means a weight loss study.
Four aspects were – and still are – surprising:
1. The magnitude of weight loss. As stated above, 26 kg in the excessively obese (obesity grade III), 20 kg in obesity grade II.
2. The shape of the curve: weight loss was steady and progressive, with statistical significance each year compared to the previous year. There was no weight regain which seems unique, even and particularly compared to weight loss studies.
3. The fact that every single obese man lost weight.
4. The fact that we had almost no drop-outs
MedicalResearch: What should clinicians and patients take away from your report?
Dr. Saad: There is a very low awareness of hypogonadism. Testosterone is associated with sexual functions but, as a matter of fact, it has numerous effects on multiple organ systems. Especially the metabolic effects are striking. According to an increasing number of studies, testosterone deficiency is highly prevalent (up to 50 per cent) in men with obesity, but also in men with type 2 diabetes – who are often obese. Clinicians should consider measuring testosterone in these men, and patients may ask their doctors to have their testosterone measured. Fasting blood samples should be taken in the morning. Of course, the same sample can be used for blood glucose, lipids, etc. When levels are low on two separate occasions, symptoms present (the most frequent being low libido, erectile dysfunction, reduced morning erections, fatigue, but also an increased waist size) and contraindications excluded, testosterone treatment may be considered.
MedicalResearch: What recommendations do you have for future research as a result of this study?
Dr. Saad: Our results clearly call for a large-scale, placebo-controlled study in obese men with or without type 2 diabetes. The duration should be at least two years. There are open questions as to why hypogonadal men lose weight on testosterone treatment. For instance, is there a change in behavior such as an increase in physical activity? Is there a change in energy consumption (basal metabolic rate)? Both questions have not been addressed by our studies as the results were unexpected.