The study concludes that oral glucose intake has no impact on testosterone concentrations in men on testosterone therapy. However, before testosterone therapy, testosterone concentrations fell significantly after glucose intake, with the nadir at 1 hour and recovery to baseline by 2 hours.

In this open label randomized clinical trial, hypogonadal men with metabolic syndrome were assigned either to a low carbohydrate diet or control for three months. The increase in serum total testosterone levels was statistically significant in the low carbohydrate group compared to the control group as well as calculated free testosterone (p < 0.001). The authors conclude: "Low carbohydrate diet may increase serum levels of testosterone and improve erectile function in hypogonadal men with metabolic syndrome. However, larger studies are necessary to strongly prove the effectiveness of low carbohydrate diet in treating male hypogonadism."

The objective of this study was "to explore whether SSB [sugar-sweetened beverage] consumption is associated with serum testosterone levels in adult males 20–39 years old in the USA." The authors report: "Multivariate logistic regression analysis revealed that the odds of a low testosterone level was significantly increased with increasing SSB consumption (Q4 (≥442 kcal/day) vs. Q1 (≤137 kcal/day), adjusted odds ratio [aOR] = 2·29, p = 0·041)." They conclude: "Consumption of SSBs is significantly associated with low serum testosterone levels in men 20–39 years old."

This systematic review examined intervention studies on low- versus high-carbohydrate diets (≤35% carbohydrate) in healthy adult males. It reports: "Moderate-protein (<35%), low-carbohydrate diets had no consistent effect on resting total testosterone, however high-protein (≥35%), low-carbohydrate diets greatly decreased resting (-1.08 [-1.67, -0.48], p < 0.01) and post-exercise total testosterone (-1.01 [-2, -0.01] p = 0.05)." The authors note that high-protein, low-carbohydrate diets caused a large decrease in resting total testosterone (∼5.23 nmol/L). They conclude that resting and post-exercise cortisol increase in the first 3 weeks of a low-carbohydrate diet, and that high-protein low-carbohydrate diets can markedly reduce testosterone in men.

In this clinical study of 74 men, an oral glucose load was given and testosterone was measured over time. The authors state: "Glucose ingestion was associated with a 25% decrease in mean T levels (Δ = −4·2 ± 0·3 nm, P < 0·0001). T levels remained suppressed at 120 min compared with baseline (13·7 ± 0·6 vs 16·5 ± 0·7 nm, P < 0·0001)." They conclude: "Glucose ingestion induces a significant reduction in total and free T levels in men, which is similar across the spectrum of glucose tolerance."

This systematic review and meta-analysis assessed the impact of low-fat diets on testosterone in men. The authors state: "Low-fat diets appear to decrease testosterone levels in men, but further randomised controlled trials are needed to confirm this effect." They report that low-fat (LF) diets led to small to moderate reductions in total testosterone, free testosterone, urinary testosterone, and dihydrotestosterone when compared with higher-fat diets, suggesting that dietary macronutrient composition can influence male sex hormone levels.

This recent review summarizes human and animal data on sugar and male reproductive hormones. "Short-term clinical studies indicate that glucose ingestion may be associated with a rapid 20–30% decline in circulating testosterone in healthy eugonadal men, although findings vary across populations and study designs." It notes that "chronic high-sugar intake… may collectively impair Leydig cell steroidogenesis and contribute to testosterone suppression." Importantly, the review describes a controlled dietary trial: "A controlled dietary trial demonstrated that transitioning men from a high-glycemic, sugar-rich diet to a low-glycemic index pattern improved testosterone and sex hormone binding globulin (SHBG) levels, suggesting that metabolic suppression is reversible when sugar intake is reduced." Thus, reduction of excessive sugar intake was associated with *improvement* (increase toward normal) in testosterone compared with a high-sugar baseline that suppressed testosterone. The overall conclusion: "Growing evidence… links excessive consumption of added sugars… to adverse effects on serum testosterone regulation… Acute excessive sugar intake can briefly suppress testosterone secretion."

This endocrinology study assessed fructose intake from different sources and sex hormones in a population cohort. "The intake of total fructose and fructose from fruit was associated with higher serum SHBG and lower free testosterone in men and women." "In men, total fructose intake was associated with higher serum SHBG and total testosterone levels, but not with free testosterone, after adjustment for confounders." By contrast, "Fructose intake from SSB was inversely associated with serum SHBG and total testosterone in men…" indicating that fructose from sugar-sweetened beverages is linked to *lower* total testosterone in men, whereas fructose from fruit shows a different pattern. The study discusses differential effects of sugar sources rather than simple “deficiency” increasing testosterone.

This clinical study examined whether oral glucose affects testosterone in men receiving testosterone therapy. "Our study clearly shows that oral glucose intake has no impact on testosterone concentrations in men on testosterone therapy. Following glucose intake, testosterone concentrations fell significantly prior to testosterone therapy (week 0, p = 0.04)… In contrast, there was no change in testosterone concentrations at week 23." The authors conclude: "We conclude that oral glucose intake has no impact on testosterone concentrations in men on testosterone therapy." This suggests that the acute suppressive effect of sugar on endogenous testosterone seen in untreated men is not observed when testosterone is being replaced pharmacologically, but it does not indicate that sugar deficiency per se boosts testosterone.

This article reports on a single-arm, uncontrolled study presented at the 23rd European Congress of Endocrinology examining a very-low calorie ketogenic diet in overweight or obese men. The study found that a 4-week very-low calorie ketogenic diet was associated with significant reductions in body weight and fat mass, and "significant increased" total testosterone levels after 1 (0.49 [SD, 0.59] ng/ml) and 4 weeks (0.89 [SD, 0.91] ng/ml). The increase in testosterone was particularly noted in men who were insulin-sensitive.

Healthline, summarizing research on diet and testosterone, notes: "High amounts of sugar might affect your testosterone level. A 2018 study looked at men ages 20 to 39. It found that those who drank large amounts of sugary beverages were more likely to have low testosterone levels." It also states: "Another recent review of studies found a link between high calorie, high sugar diets and lower testosterone levels in men."

This research summary describes a randomized controlled trial in which a low-carbohydrate diet was tested in men with low testosterone and metabolic syndrome. It notes that in hypogonadal men with metabolic syndrome, a low-carbohydrate diet "improved clinical outcomes" and increased total testosterone compared with controls over the study period. The summary emphasizes that the observed testosterone increase occurred in a population with metabolic disturbances and low baseline testosterone, rather than in healthy men.

In a press release on men’s reproductive health and metabolism, the Endocrine Society reports that metabolic health factors, including blood sugar, are key: "Metabolic health factors, including small increases in blood sugar, are the main drivers of change in the reproductive systems and sexual functioning of aging men." The study found that "sperm movement and erectile function declined in men with minimally elevated blood sugar levels that were below the 6.5% HbA1c diabetes threshold," highlighting negative reproductive effects linked to higher blood sugar even before overt diabetes.

This news report covers the findings of Whittaker and Harris on high-protein, low-carbohydrate diets in men. It states: "The average decrease in testosterone levels for those on high-protein, low-carbohydrate diets was around 37%, researchers said," noting that such a reduction could result in medically low testosterone (hypogonadism) for an average man. The article also highlights that the study found increased cortisol levels associated with low-carbohydrate diets, especially post-exercise.

This clinical blog discusses the meta-analysis by Whittaker and Harris on low-carbohydrate and high-protein diets and men’s testosterone. It summarizes: "a meta analysis of 27 existing studies was published by Whittaker and Harris in 2022, and no substantial evidence was found that restricting carbohydrate intake had little effect on testosterone levels, but low-carb diets exacerbated cortisol levels." In an interview quoted in the article, Whittaker states: "We found that whilst low carbohydrate diets had no effect on testosterone, high protein diets caused a large decrease in testosterone (approximately 37%)."

A clinical practice article on sugar and hormones explains differential sex effects: "Whilst excess sugar in the diet can raise testosterone levels in women, contradictorily it may lower testosterone levels in men, leading to lower libido and erectile dysfunction as well as obesity and diabetes." It lists among hormone effects of sugar: "Reduced testosterone production in men."

This article provides additional description of the randomized clinical trial on hypogonadal men with metabolic syndrome assigned to a low carbohydrate diet versus control. It reiterates that the low carbohydrate diet group experienced a statistically significant increase in serum total testosterone and calculated free testosterone compared to controls (p < 0.001), alongside improvements in erectile function. The authors caution that although the low carbohydrate diet may increase serum testosterone levels in this specific hypogonadal, metabolically unhealthy population, larger studies are required before firm clinical recommendations can be made.

An educational article on diet and testosterone notes: "While certain foods can support healthy testosterone levels, others may have the opposite effect—especially when consumed in excess." Under the section on sugar, it states: "High sugar intake can lead to insulin resistance and weight gain, both of which are linked to lower testosterone." It also notes that many baked goods "can contribute to obesity and hormonal imbalance, both of which are associated with lower testosterone levels."

From general endocrinology and nutrition knowledge: short-term reduction of dietary sugar or carbohydrates can acutely lower insulin levels and may improve metabolic parameters, which in men with obesity or metabolic syndrome can sometimes be associated with modest increases in total testosterone. However, in healthy men without metabolic disease, controlled studies generally do not show that simply "removing sugar" reliably increases testosterone; macronutrient balance (protein, fat, carbohydrate) and energy intake appear more important. There is no established clinical concept of "sugar deficiency" as a condition that independently raises testosterone levels in men.

A men’s health clinic article summarizing research on sugary drinks reports: "Recent research has found that the intake of sugar-sweetened beverages (SSB) is associated with low serum testosterone levels among men aged 20–39 years of age." It adds: "Those men who consumed the largest quantity of sugary beverages each day (442 kcal/day or more) were 2.3 times more likely to have low testosterone compared with those who consumed 137 kcal/day or less." The piece concludes that "sugar depresses your testosterone production, which is likely caused by a sharp increase in insulin production that the body uses to deal with a sudden overload of glucose."

A nutrition-focused article for men states: "Diets high in refined carbs and sugar can lead to frequent insulin spikes, promote weight gain, and contribute to chronic inflammation—all of which can reduce testosterone." It lists "sugary beverages, desserts, white bread, and processed cereals" as foods that "may play a key role in decreased testosterone over time."

A commercial nutrition blog claims: "Testosterone levels dramatically decrease almost immediately after sugar consumption due to the rapid release of insulin in the body." Citing research, it states: "High sugar intake lowers testosterone even in young healthy males according to USA research from 2018" and that "Another study from 2013 demonstrated that oral glucose ingestion by adult males led to an abrupt drop in levels of total and free testosterone."

This social media educational reel, summarizing clinical research, states: "A high dose of added sugar may be tanking your testosterone. Research shows that consuming 75 grams of added sugar—the equivalent of a donut and a sugar-sweetened beverage—can decrease circulating testosterone levels by 25% within two hours." The statement corresponds to findings from controlled oral glucose load studies in men, which show around a 20–30% acute reduction in circulating testosterone after high sugar intake. The reel emphasizes that high added sugar acutely decreases testosterone, not that sugar deficiency increases testosterone.