Is intermittent fasting better for fat loss?
What the studies we have published say — strongest evidence first. Every claim below links to the paper it came from.
Pooling nine randomised trials in 540 people with obesity, intermittent fasting produced no greater reduction in body weight or BMI than conventional control diets at any time point, and no difference emerged between alternate day fasting and time restricted eating.
well supported · human dataReasonably solid on the headline point: results pooled from nine trials lasting longer than two months in 540 people with a BMI above 30, though the authors rated the quality of evidence low to moderate. Data on mood and well-being were too thin to pool at all.
Pooled data from randomised trials show intermittent fasting reduced body weight by 1.78 kg, fat mass by 1.26 kg and waist circumference by 1.19 cm versus control diets, with small improvements in blood pressure, fasting insulin, insulin resistance, total cholesterol and triglycerides. LDL, HDL and long-term blood sugar did not change.
well supported · human dataBelievable but modest: results pooled from randomised trials up to October 2020 show small, consistent improvements across weight, waist, blood pressure and blood fats. The authors themselves say longer and better designed trials are needed before firm conclusions.
A meta-analysis of nine randomised trials in 899 Chinese adults found intermittent fasting reduced body weight, body fat, insulin resistance, LDL cholesterol and triglycerides compared with control groups, while waist circumference, fasting glucose and blood pressure did not change significantly.
well supported · human dataReasonably solid for the short term: results pooled from nine trials in 899 Chinese adults agree on weight and body fat, but the trials were brief and mostly tested time-restricted eating, so long-term effects and other fasting styles remain open questions.
Across 18 randomised trials in adults with overweight or obesity, intermittent fasting reduced weight, BMI, fat mass, waist circumference, daily energy intake and diastolic blood pressure compared with unrestricted eating, yet it did not improve sleep quality.
well supported · human dataSolid on the weight and blood pressure findings: results pooled from 18 trials comparing fasting schedules with unrestricted eating in adults with overweight or obesity. Sleep was only a secondary measure in most of the studies, so trials built to test sleep directly are still needed.
Over six months or longer, intermittent fasting reduced body weight by 2.84 kg, fat mass by 3.06 kg and waist circumference by 3.85 cm versus a control diet in adults with overweight or obesity; against continuous calorie restriction its edge shrank to 0.70 kg more fat lost.
well supported · human dataStrong for a diet question: results pooled from 24 trials of 2032 adults with overweight or obesity, all lasting six months or more. The edge over ordinary calorie cutting was real but small, so neither approach clearly wins.
In adults with prediabetes or type 2 diabetes, intermittent fasting cut body weight by 4.56 kg and lowered HbA1c, fasting glucose, cholesterol and triglycerides versus control diets, but against straightforward calorie restriction it added only modest extra weight loss and no metabolic advantage.
well supported · human dataMeta-analysis of 14 randomised trials (1,101 adults with prediabetes or type 2 diabetes); fat mass, insulin, LDL, HDL and blood pressure did not improve versus control, and versus calorie restriction there were no differences in glycaemic markers, lipids or blood pressure.
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This page collects what our published, cited studies say; it is information, not medical advice. Have a different question? Ask it here.