Single-Arm Study Finds Very-Low Calorie Ketogenic Diet Could Improve Testosterone Levels in Men

Angelo Cignarelli, MD, PhD

New research suggests a low calorie ketogenic diet could help improve body weight and testosterone levels in men who are overweight.

Presented at the 23rd European Congress of Endocrinology (e-ECE 2021), the single-arm study found implementing a very-low calorie ketogenic diet was associated with increased total testosterone levels, especially in patients who were insulin-sensitive, after just 4 weeks.

“We aimed to evaluate the response of total testosterone and sex hormone levels to a very-low calorie ketogenic diet in a cohort of overweight or obese non-diabetic male subjects and what we found was that there is a noticeable relation between a specific, controlled diet and insulin action, energy balance, and testicular function,” said Angelo Cignarelli, MD, PhD, assistant professor at the University of Bari in Italy, in a statement.

With the prevalence of obesity exploding in recent decades and rates expected to continue rising, new emphasis has been placed on the impact of nutrition among people with overweight or obesity. To learn more about the effects of certain dietary approaches on health, Cignarelli and colleagues from the University of Bari designed the current study as a single-arm, uncontrolled study assessing the impact of a 4-week, low-calorie ketogenic diet on body weight, fat mass, BMI, and sex hormone levels in 17 men considered to be overweight or obese.

At baseline, the mean age of the cohort was 41.3 (SD, 12.2) years, the mean BMI was 36.4 (SD, 5.2) kg/m2, and the mean TT was 2.5 (SD, 1.0) ng/ml. Of note, the very-low calorie ketogenic diet used in the study advised patients to reduce their daily calorie intake to less than 800.

All patients included in the study were advised to follow this diet and underwent assessments of anthropometric parameters, oral glucose tolerance testing (OGTT), bioelectrical impedance analysis, and blood testing for the measurement of glycemia, insulin, total testosterone (TT), sex hormone binding globulin (SHBG), and luteinizing hormone (LH) performed before and after 1 and 4 weeks of very-low calorie ketogenic diet.

Upon analysis, investigators found use of a very-low calorie ketogenic diet was associated with significant reductions in body weight (-9.3 [SD, 1.8] kg), fat mass (-6.5 [SD, 2.1] kg), and BMI (-3.1 [SD, 0.7]). Additionally, results indicated a mean loss of 14.9±3.9% of initial body weight was achieved among the study population at 4 weeks.

When assessing serum TT levels, a very-low calorie ketogenic diet was associated with significant increased after 1 (0.49 [SD, 0.59] ng/ml) and 4 weeks (0.89 [SD, 0.91] ng/ml). Further analysis indicated a similar trend for serum SBHG levels after 1 (3.47 [SD, 4.73] nmol/l) and 4 weeks (10.94 [SD, 12.87] nmol/l) of very-low calorie ketogenic diet.

Investigators noted additional analyses stratifying patients according to high and low responders based on TT variations after 1 week indicated responders differed only by level of insulin sensitivity. Investigators also pointed out low responders displayed a significantly high level of insulinemia compared to those considered high responders.

Investigators noted the design of their study limitations the applicability of results and called for further research into the effects of a very-low calorie ketogenic diet on additional clinical outcomes.

This study, “Effects of a very low-calorie ketogenic diet on androgen levels in overweight/obese men: a single-arm uncontrolled study,” was presented at e-ECE 2021.