News | New evidence: ketogenic diets may improve weight, insulin and androgen levels in PCOS over the short term
A systematic review and meta-analysis in the British Journal of Nutrition provides new evidence on dietary interventions for women with polycystic ovary syndrome (PCOS). A professionally supervised very-low-carbohydrate ketogenic diet (VLCKD) significantly reduced body weight and abdominal fat while improving insulin resistance and lowering androgen levels, offering measurable short-term benefits for menstrual irregularity, metabolic burden and fertility goals. The team stressed that long-term safety, adherence and differences among PCOS phenotypes require further study.
The metabolic and lifestyle challenges of PCOS make VLCKD a research focus
About one in ten women of reproductive age worldwide has PCOS, characterized by insulin resistance, weight gain, low-grade inflammation and high androgen levels. Even modest weight loss can improve cycles and fertility potential, but many intensive diets are hard to maintain. By inducing nutritional ketosis, reducing insulin and decreasing visceral fat, VLCKD is considered a potentially practical option. Existing trials are short and use varied protocols, however, so researchers remain cautious about long-term use.
Systematic review includes 12 RCTs and more than 800 women with PCOS
Following PRISMA methods and registering the protocol with PROSPERO, the team included 12 randomized controlled trials from Italy, China, Pakistan, the United States and other countries; 11 entered the meta-analysis. Interventions lasted 4–24 weeks and ranged from 750–800 kcal VLCKDs to energy-restricted VLCKDs of 1300–1500 kcal, all using strict carbohydrate restriction to maintain ketosis.
The study assessed three outcome categories:
(1) Anthropometric measures: weight, BMI, waist circumference, fat mass and waist-to-hip ratio;
(2) Hormones: sex hormone-binding globulin (SHBG), LH, FSH, and free and total testosterone;
(3) Metabolic measures: fasting glucose, insulin, HOMA-IR and blood lipids.
Substantial reductions in weight, fat and waist circumference
The meta-analysis found clear weight-management effects:
Average weight reduction: 9.57 kg
Waist circumference reduction: 7.75 cm
Fat mass reduction: 7.44 kg
BMI reduction: 3.45 kg/m²
In daily life, these changes correspond to a smaller waist, less joint strain and improved sleep. Although heterogeneity was high for several outcomes (I²>90%), sensitivity analyses showed consistent directions of effect and funnel plots showed no clear publication bias.
Lower androgens and higher SHBG suggest improved ovulatory potential
VLCKD also produced hormonal improvements:
Free testosterone decreased by 0.31 ng/dL
Total testosterone decreased by 7.21 ng/dL
SHBG increased by 15.22 nmol/L
LH and the LH/FSH ratio decreased
FSH did not change significantly
Overall, lower androgens and more stable reproductive-axis hormones may support recovery of regular ovulation.
Improved insulin and glucose control may reduce long-term metabolic risk
Metabolic measures also improved:
Fasting glucose decreased by 9.65 mg/dL
Fasting insulin decreased by 2.41 μIU/mL
HOMA-IR improved by 2.46
This may mean steadier energy and fewer sudden episodes of fatigue or hypoglycemia-like symptoms. Triglycerides decreased significantly, while total cholesterol, LDL-c and HDL-c showed no consistent pattern.
Evidence limitations: short trials, high heterogeneity and limited long-term follow-up
The team identified common limitations:
Short interventions that cannot assess long-term safety
Substantial dietary variation causing high statistical heterogeneity
Inadequate randomization in some trials
No stratified analysis by PCOS phenotype
Limited reporting of adverse events and adherence
Ketogenic diets may also cause short-term gastrointestinal discomfort, nutritional gaps or changes in some lipid measures, making professional supervision and cyclical carbohydrate reintroduction especially important.
Effective in the short term, but large, long-term real-world studies are still needed
Current evidence shows that VLCKD can improve weight, metabolism and androgen levels in women with PCOS over the short term and may improve fertility-related measures. Researchers called for longer, better-controlled studies that distinguish PCOS phenotypes and include behavioral support to fully assess sustainability and safety.
News | New evidence: ketogenic diets may improve weight, insulin and androgen levels in PCOS over the short term
News | New evidence: ketogenic diets may improve weight, insulin and androgen levels in PCOS over the short term
A systematic review and meta-analysis in the British Journal of Nutrition provides new evidence on dietary interventions for women with polycystic ovary syndrome (PCOS). A professionally supervised very-low-carbohydrate ketogenic diet (VLCKD) significantly reduced body weight and abdominal fat while improving insulin resistance and lowering androgen levels, offering measurable short-term benefits for menstrual irregularity, metabolic burden and fertility goals. The team stressed that long-term safety, adherence and differences among PCOS phenotypes require further study.
The metabolic and lifestyle challenges of PCOS make VLCKD a research focus
About one in ten women of reproductive age worldwide has PCOS, characterized by insulin resistance, weight gain, low-grade inflammation and high androgen levels. Even modest weight loss can improve cycles and fertility potential, but many intensive diets are hard to maintain. By inducing nutritional ketosis, reducing insulin and decreasing visceral fat, VLCKD is considered a potentially practical option. Existing trials are short and use varied protocols, however, so researchers remain cautious about long-term use.
Systematic review includes 12 RCTs and more than 800 women with PCOS
Following PRISMA methods and registering the protocol with PROSPERO, the team included 12 randomized controlled trials from Italy, China, Pakistan, the United States and other countries; 11 entered the meta-analysis. Interventions lasted 4–24 weeks and ranged from 750–800 kcal VLCKDs to energy-restricted VLCKDs of 1300–1500 kcal, all using strict carbohydrate restriction to maintain ketosis.
The study assessed three outcome categories:
(1) Anthropometric measures: weight, BMI, waist circumference, fat mass and waist-to-hip ratio;
(2) Hormones: sex hormone-binding globulin (SHBG), LH, FSH, and free and total testosterone;
(3) Metabolic measures: fasting glucose, insulin, HOMA-IR and blood lipids.
Substantial reductions in weight, fat and waist circumference
The meta-analysis found clear weight-management effects:
Average weight reduction: 9.57 kg
Waist circumference reduction: 7.75 cm
Fat mass reduction: 7.44 kg
BMI reduction: 3.45 kg/m²
In daily life, these changes correspond to a smaller waist, less joint strain and improved sleep. Although heterogeneity was high for several outcomes (I²>90%), sensitivity analyses showed consistent directions of effect and funnel plots showed no clear publication bias.
Lower androgens and higher SHBG suggest improved ovulatory potential
VLCKD also produced hormonal improvements:
Free testosterone decreased by 0.31 ng/dL
Total testosterone decreased by 7.21 ng/dL
SHBG increased by 15.22 nmol/L
LH and the LH/FSH ratio decreased
FSH did not change significantly
Overall, lower androgens and more stable reproductive-axis hormones may support recovery of regular ovulation.
Improved insulin and glucose control may reduce long-term metabolic risk
Metabolic measures also improved:
Fasting glucose decreased by 9.65 mg/dL
Fasting insulin decreased by 2.41 μIU/mL
HOMA-IR improved by 2.46
This may mean steadier energy and fewer sudden episodes of fatigue or hypoglycemia-like symptoms. Triglycerides decreased significantly, while total cholesterol, LDL-c and HDL-c showed no consistent pattern.
Evidence limitations: short trials, high heterogeneity and limited long-term follow-up
The team identified common limitations:
Short interventions that cannot assess long-term safety
Substantial dietary variation causing high statistical heterogeneity
Inadequate randomization in some trials
No stratified analysis by PCOS phenotype
Limited reporting of adverse events and adherence
Ketogenic diets may also cause short-term gastrointestinal discomfort, nutritional gaps or changes in some lipid measures, making professional supervision and cyclical carbohydrate reintroduction especially important.
Effective in the short term, but large, long-term real-world studies are still needed
Current evidence shows that VLCKD can improve weight, metabolism and androgen levels in women with PCOS over the short term and may improve fertility-related measures. Researchers called for longer, better-controlled studies that distinguish PCOS phenotypes and include behavioral support to fully assess sustainability and safety.
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