Browse the evidence

Alternate-day fasting (ADF) and whole-day fasting protocols effectively reduce body weight, body fat, total cholesterol, and triglycerides in normal-weight, overweight, and obese adults over short-term periods (3-24 weeks).

To lose weight and improve cholesterol, try alternating between normal eating days and fasting days where you eat only one small meal (about 25% of your daily calories). Alternatively, fast completely or partially for 1-2 days a week. Stick to this for at least 3 weeks to see results. This approach works for various body types and is often easier to sustain than daily calorie counting.

Commercial weight-loss programs Weight Watchers and Jenny Craig produce statistically significant and clinically relevant greater weight loss compared to control or behavioral counseling interventions at 12 months.

If you are overweight or obese, joining a high-intensity commercial program like Weight Watchers or Jenny Craig is a clinically supported strategy for losing weight. These programs provide structure, accountability, and social support that lead to better results than trying to lose weight alone or with basic education. Expect to lose at least 2.6% more body weight with Weight Watchers and 4.9% more with Jenny Craig compared to no program after one year. While they cost money, they may be cost-effective compared to other treatments.

Sustained calorie restriction (1750–2100 kcal/day) in healthy, non-obese humans significantly improves cardiovascular and metabolic biomarkers, including reducing BMI, blood pressure, fasting insulin, glucose, and cholesterol, while maintaining excellent physical and mental health.

To improve metabolic health, you can adopt a calorie-restricted diet focused on nutrient density. Aim for 1750-2100 kcal daily, prioritizing complex carbohydrates, vegetables, and fruits, while ensuring you get adequate protein and essential vitamins. This approach has been shown to significantly lower BMI, blood pressure, insulin, and cholesterol in healthy adults without compromising physical or mental performance, provided the diet is well-planned and nutrient-rich.

Very low calorie diets (VLCDs) providing less than 800 kcal/day produce rapid, large weight losses (average 20 kg in 12 weeks) in moderately to severely obese adults, significantly outperforming conventional behavioral or pharmacological treatments.

If you have severe obesity, a medically supervised VLCD (under 800 calories/day) is the most effective non-surgical way to lose weight quickly, averaging 20kg in 3 months. It is not safe to do this alone; you need medical monitoring, high-quality protein, and supplements to prevent heart and muscle damage. The main challenge is keeping the weight off after you stop.

Male-only weight loss interventions are effective at producing clinically significant weight loss (mean reduction >5%) when they include specific structural components: younger participant age, high contact frequency (>2.7 times/month), face-to-face group delivery, and prescribed energy restriction.

If you are a man looking to lose weight, look for programs specifically designed for men. The most effective ones involve meeting with a group in person more than twice a month and include a clear plan for reducing your calorie intake. These structural elements seem to help men stick with the program and lose a significant amount of weight.

Modified alternate-day fasting (ADF) significantly reduces body weight, BMI, waist circumference, and blood pressure in overweight/obese women over a 6-week period.

Try a modified alternate-day fasting schedule for 6 weeks. Eat very little (about 25-30% of your needs) on 3 specific days (e.g., Sat, Mon, Wed) and eat normally (around 1700-1800 kcal) on the other 3 days. This approach significantly reduces weight and blood pressure in obese women, potentially offering a more flexible alternative to daily dieting.

A 45-day very-low-calorie ketogenic diet (VLCKD) incorporating whey protein improves muscle strength preservation and yields a healthier gut microbiota profile (increased Bacteroidetes, decreased Firmicutes) compared to vegetable or animal protein sources.

If you are doing a strict low-calorie ketogenic diet, choose whey protein as your primary supplement source. This study suggests it helps preserve muscle strength better than animal proteins (meat/fish/eggs) and promotes a healthier gut bacteria balance. Aim for about 90g of protein daily spread across 5 meals, keeping total calories around 780, and monitor your ketosis via urine strips to ensure you stay in the metabolic state.

Lifestyle interventions incorporating physical activity significantly reduce body weight (mean difference 8.9 kg) and BMI (2.8 kg/m²) in individuals with Class II and III obesity (BMI ≥ 35 kg/m²).

For individuals with Class II or III obesity, combining dietary changes (specifically caloric restriction) with physical activity leads to significant weight loss (averaging nearly 9 kg) and improved health markers. The intensity and supervision of the exercise can vary, but consistent engagement in these lifestyle changes is effective for this population.

Lifestyle interventions with physical activity significantly improve specific cardiometabolic risk factors (fat mass, waist circumference, blood pressure, total cholesterol, LDL-C, triglycerides, fasting insulin) in Class II and III obese individuals, but do not significantly affect HDL-C or fasting blood glucose.

While lifestyle changes improve blood pressure, cholesterol, and insulin sensitivity in severe obesity, they may not automatically normalize HDL cholesterol or fasting blood glucose levels for everyone. Monitoring these specific markers is important even if weight loss is achieved.

Restricting energy intake between 19:00 and 06:00 hours significantly reduces total daily energy intake and body weight in healthy young men over a short-term (2-week) period.

To reduce your daily calorie intake without counting calories, stop eating after 7 PM. This study shows that simply avoiding food between 7 PM and 6 AM led to a significant drop in daily energy intake and weight loss in young men over two weeks. You can drink water during this window. This is a simple 'small-changes' approach that may help prevent weight gain.

A proprietary weight loss program combining a 12-week very-low-calorie diet (VLCD) with behavioral lifestyle modification achieves long-term weight maintenance (≥5% loss) in a substantial portion of patients with marked obesity, despite significant initial weight regain.

To achieve long-term weight loss, consider a structured program that starts with a short period (12 weeks) of very low-calorie intake (400-800 kcal) followed by a gradual transition to normal foods and behavioral counseling. Success is defined as maintaining at least 5% of your initial weight loss, even if you regain some weight in the first few years. This approach has been shown to work for a significant portion of people with marked obesity over 5 years.

A structured 12-month primary care program using a low-energy liquid diet (LELD) followed by food reintroduction and maintenance achieves a clinically significant, sustained weight loss of ≥15 kg in approximately one-third of severely obese patients (BMI ≥40 kg/m2).

If you have severe obesity (BMI 40+), a structured program using a low-calorie liquid diet for 12 weeks, followed by a gradual return to solid foods and maintenance support, can help you lose and keep off at least 33 pounds (15 kg). This approach is feasible in regular doctor's offices and costs much less than surgery, offering a viable alternative for those who cannot access or prefer not to have surgery.

Adherence to a Protein-Sparing Modified Fast (PSMF) for 17+ weeks results in significant weight loss (mean 47 lbs) and improved cardiovascular markers (blood pressure, triglycerides) in obese outpatients.

To lose significant weight and improve blood pressure, you can use a supervised, very low-calorie diet (under 800 calories) that includes high-quality protein (1.5g per kg of your ideal weight). This must be done under medical supervision, combined with education and exercise, and typically lasts around 17 weeks.

PSMF leads to significant reductions in systolic and diastolic blood pressure, fasting blood sugar, and serum triglycerides.

Losing weight through this diet significantly improves your blood pressure, blood sugar, and triglyceride levels.

Adherence to a Spanish Ketogenic Mediterranean Diet (SKMD) for 12 weeks significantly reduces body weight, BMI, systolic and diastolic blood pressure, total cholesterol, LDL, triglycerides, and fasting glucose, while increasing HDL in obese adults.

Follow a Spanish Ketogenic Mediterranean Diet for 12 weeks. Eat unlimited calories but restrict carbohydrates to under 30g daily (from green vegetables/salads). Include at least 30ml of virgin olive oil and 200-400ml of red wine daily. Prioritize fish for protein. Take a daily multivitamin and calcium supplement. Expect significant weight loss and improved blood markers without needing to count calories.

A modified ketogenic Mediterranean diet (KEMEPHY) with phytoextracts significantly reduces body weight, BMI, and fat mass while improving cardiovascular risk markers (lipid profile and glucose) in overweight/obese adults over a 6-week period.

Follow a 6-week diet plan that starts with very low carbs (approx 34g/day) and high protein/fat, focusing on green vegetables, fish, meat, and olive oil. Use specific protein-based substitutes that mimic pasta/bread to maintain satisfaction. After 3 weeks, gradually introduce moderate carbs (50-80g/day). Take daily supplements including specific herbal extracts to help with energy and digestion. Expect significant weight loss and improved blood markers.

An 8-week hypocaloric, very low-carbohydrate diet (≤71g carbs/day) in overweight women promotes significant weight loss, improved blood pressure, and improved lipid profiles (lowered LDL, TAG, and TAG/HDL ratio) without compromising glucose tolerance.

For overweight women, reducing daily carbohydrates to around 70 grams and creating a caloric deficit for 8 weeks can lead to significant weight loss and improvements in blood pressure and cholesterol without negatively affecting blood sugar control. This approach does not require increasing fat or protein intake, and it maintains HDL levels.

A 12-week telenutrition intervention consisting of weekly registered dietitian support via video and phone, combined with a moderate caloric deficit, significantly increases the proportion of middle-aged and older men with cardiovascular risk factors who achieve clinically significant weight loss (≥5% body weight) compared to enhanced usual care alone.

If you are a man over 40 with excess weight and heart disease risks, you can lose significant weight (over 5% of your body) by following a moderate calorie-reduced diet and getting weekly support from a dietitian via phone or video. You don't necessarily need expensive in-person visits; consistent check-ins and tracking your weight and food intake are key. This approach works well even if you live in a rural area, provided you have internet access.

A short-term low-calorie diet intervention (approx. 5,023 kJ/day) significantly reduces serum advanced glycation end products (AGEs) in healthy overweight or obese adults, with the reduction correlating with decreases in BMI, waist circumference, and triglycerides.

If you are overweight or obese, adopting a low-calorie diet that creates a caloric deficit (specifically around 1,200 kcal/day in this study) for two months can significantly lower your blood levels of Advanced Glycation End Products (AGEs). This reduction is linked to your weight loss and improved lipid profiles, suggesting a direct benefit to reducing inflammation and cardiovascular risk markers through simple caloric restriction.

A 30-day ketogenic diet (KD) with adequate protein intake (1.8 g/kg/day) reduces body fat and visceral adipose tissue in semi-professional soccer players without compromising muscle mass, maximal strength, or intermittent aerobic performance.

If you are a semi-professional soccer player looking to lose fat quickly, a 30-day ketogenic diet can work without hurting your strength or performance. Key requirements: 1) Keep carbohydrates under 30g/day. 2) Eat 1.8 grams of protein per kilogram of body weight daily. 3) Maintain your normal training schedule. 4) Use supplements or specific foods to help with adherence and electrolyte balance. Monitor your ketones to ensure you are in ketosis.

Intermittent Energy Restriction combined with a Mediterranean diet (IER+MED) significantly reduces visceral adipose tissue (VAT) and total fat mass more effectively than a continuous euenergetic DASH diet over 12 weeks.

To reduce visceral fat, try restricting calories to 30% of your normal intake for two consecutive days each week, while eating a Mediterranean-style diet (rich in plants, olive oil, fish) on the other five days. This approach may reduce belly fat more effectively than just eating a healthy diet every day without restriction. Ensure you are physically active, aiming for an hour of moderate exercise most days.

Combining a very-low-energy diet (VLED) with behavior therapy (BT) produces significantly greater 5-year weight maintenance than behavior therapy alone in morbidly obese patients, particularly men.

For morbid obesity, combining a short, strict very-low-energy diet (approx. 500 kcal) with behavioral therapy leads to significantly better long-term weight loss (5 years) than behavioral therapy alone. This is especially true for men. While dropout rates are higher with the diet, those who stick with it see much better results. You do not necessarily need a separate maintenance program if the initial behavioral training is robust.

Intermittent energy restriction (IER) involving 2-3 fasting days per week produces greater short-term absolute weight loss and percentage of weight loss compared to continuous energy restriction (CER) when total energy deficit is matched.

If you struggle with daily calorie counting, try restricting calories to 400-600 kcal on 2-3 days a week (fasting days) and eating normally on the other days. This method may help you lose more weight in the short term (under 6 months) than eating slightly less every day, provided your total weekly calories are similar to the daily restriction approach.

Combining resistance training with a caloric deficit maximizes fat mass loss in overweight/obese premenopausal women compared to diet or resistance training alone.

To lose the most fat while keeping your muscle, combine a moderate caloric deficit with a high-protein diet and resistance training. Do not skip the weights just because you are dieting; they are crucial for preserving your metabolic engine and lean tissue. Aim for 3 days of strength training per week, focusing on compound movements with 10-12 reps, and ensure you are eating enough protein (around 1.4g per kg of body weight) to support your muscles during the deficit.