Browse the evidence

Time-restricted eating (TRE) with an 8-hour daily eating window significantly reduces body weight and fat mass in adults with obesity compared to control groups, particularly when the intervention lasts longer than 12 weeks.

If you have obesity, try restricting your eating to an 8-hour window each day (e.g., 10 AM to 6 PM). This approach is more effective for weight and fat loss than no time restriction, especially if you stick with it for more than 3 months. While it doesn't significantly change blood sugar or cholesterol markers in obese adults, it is a viable strategy for weight management. Be aware that adherence may be challenging due to social obligations, so consistency is key.

Intermittent Energy Restriction (IER) diets, including Alternate-Day Fasting (ADF) and Time-Restricted Feeding (TRF), produce weight loss and metabolic improvements (reduced triglycerides, LDL, and blood pressure) that are comparable to Continuous Energy Restriction (CER) diets when total caloric intake is matched.

If you struggle with daily calorie counting, try Intermittent Energy Restriction. You can either fast on alternate days (eating very little or nothing on fast days) or restrict your eating to a specific window (e.g., 8 hours) each day. The goal is to reduce total weekly calories, not necessarily to eat less every single day. Expect to lose about 3-8% of your body weight over 2-3 months, similar to what you would get from eating less every day.

Interval training (HIIT and SIT) produces significantly greater reductions in total body fat percentage compared to moderate-intensity continuous training (MICT) and non-exercise control (CON) in apparently healthy adults.

If you want to lose body fat, interval training (HIIT or SIT) is more effective than steady-state cardio (MICT) or no exercise. You don't need to do long sessions; even low-volume HIIT (under 15 minutes of high-intensity work per session) can be superior. This is especially true if you have overweight or obesity, or if you stick with the program for at least 12 weeks.

A very-low-calorie diet (VLCD, ≤800 kcal/day) produces significantly greater weight loss and more pronounced improvements in hyperandrogenemia (Free Androgen Index) and metabolic markers compared to a moderate energy deficit diet in obese women with PCOS over an 8-week period.

For obese women with PCOS seeking rapid hormonal and weight improvement, a medically supervised VLCD (800 kcal/day) for 8 weeks is significantly more effective than standard moderate dieting. It achieves nearly triple the weight loss and can induce biochemical remission of PCOS symptoms, which moderate dieting failed to do in this trial. This requires strict adherence to meal replacements and medical oversight.

Tirzepatide significantly reduces body weight, BMI, and waist circumference in overweight or obese adults without diabetes compared to placebo.

If you are overweight or obese and do not have diabetes, tirzepatide is a highly effective prescription medication for significant weight loss. It is taken once a week by injection. While it causes side effects like nausea and vomiting in many people, the weight loss benefits are substantial. You should discuss the risks and benefits with your doctor and start with a low dose to minimize side effects.

Intermittent fasting (IF) significantly reduces body weight, BMI, fat mass, and triglycerides compared to regular diet in overweight/obese adults aged 40+ without metabolic disease, without causing significant loss of lean body mass.

If you are over 40 and overweight, trying intermittent fasting (like time-restricted eating or alternate-day fasting) can help you lose fat and weight without losing muscle, compared to just eating normally. Stick to a 2-6 week trial to see if it works for you.

Intermittent fasting significantly reduces fat mass in overweight/obese adults aged 40+ without metabolic disease, with greater efficacy in those with lower BMI (overweight to mild obesity) and with Time-Restricted Eating (TRF) protocols.

If you use Time-Restricted Eating (TRF), you may see better weight loss results, especially if your BMI is under 32.5.

Lowering dietary energy density (ED) significantly reduces total energy intake in both children and adults without requiring portion size reduction.

To reduce calories without feeling hungry, focus on lowering the energy density of your meals. This means increasing the proportion of water-rich foods (like vegetables) and decreasing energy-dense components (like fats and sugars). You can eat the same amount of food by weight, or even more, while consuming significantly fewer calories.

Time-restricted eating (TRE) with an 8-hour or shorter eating window significantly reduces body fat percentage, fat mass, lean mass, body mass, BMI, and waist circumference in adults with overweight and obesity compared to control groups.

If you are overweight or obese, try limiting your daily eating window to 8 hours or less (e.g., eating only between 12 PM and 8 PM). This approach has been shown to significantly reduce body fat, waist size, and overall weight compared to unrestricted eating. While you may lose some lean muscle mass, the overall health benefits for fat loss are significant. If you prefer a 10-12 hour window, you may not see the same level of fat loss.

A 6-month low-calorie, high-protein diet (35% of total calories from protein) improves glucose metabolism, body composition, and cardiometabolic profiles in subjects with prediabetes or type 2 diabetes and overweight/obesity, regardless of whether the protein source is primarily animal or plant-based.

If you have prediabetes or type 2 diabetes and are overweight, switching to a diet where 35% of your calories come from protein (whether from meat, fish, eggs, beans, nuts, or soy) and restricting your total calories by 30% can significantly improve your blood sugar, weight, and heart health markers. It does not matter if you choose animal or plant proteins; the key is the high-protein, low-calorie pattern itself. Stick to this for at least 6 months for best results.

Alternate-day modified fasting (ADMF) produces greater weight loss and BMI reduction compared to daily calorie restriction (CR) in overweight/obese women over 8 weeks.

If you are an overweight woman looking to lose weight, try Alternate-Day Modified Fasting. On fasting days, eat only 25% of your calculated daily calories (mostly lunch). On feeding days, eat 100% of your daily calories. Keep your macronutrient ratio at 15% protein, 30% fat, and 55% carbs. This method may help you lose more weight and stick to the diet better than eating less every day.

An intensive start with combined diet and supervised circuit weight training (0-3 months) significantly enhances long-term waist circumference reduction compared to delayed exercise or behavioral modification alone.

If you are starting a weight loss journey, especially if you have obesity, start with an intensive program that includes both diet and supervised exercise from day one. This study suggests that adding structured exercise (like circuit training) in the first 3 months leads to significantly better long-term reduction in waist circumference than starting exercise later or doing diet alone. The early success helps maintain motivation and adherence over the next few years.

Intensive behavioral modification (diet and counseling) alone results in clinically significant long-term weight loss and maintenance, even without added exercise.

You can achieve significant long-term weight loss through intensive behavioral modification alone, without needing to add structured exercise. This involves regular counseling, self-monitoring with food/activity diaries, and a moderate caloric deficit (500-1000 kcal/day). This approach resulted in an average 6.8% weight loss maintained over 3 years.

Intermittent fasting significantly reduces body weight and BMI in overweight and obese adults compared to control diets, with alternate-day fasting showing superior weight loss effects compared to time-restricted eating.

Intermittent fasting is an effective strategy for weight loss in overweight and obese individuals. Alternate-day fasting appears to offer greater weight loss benefits than time-restricted eating. To implement, choose a method (like ADF, TRE, or 5:2) that fits your lifestyle, ensuring you maintain a caloric deficit during fasting periods. Consistency over 12+ weeks yields the best results for body composition.

A eucaloric ketogenic diet (KD) induces significant weight loss primarily through visceral fat reduction while preserving muscle and bone mass, without adverse metabolic changes, over a period of up to three months.

If you are overweight or even normal weight, a ketogenic diet can help you lose fat without losing muscle, provided you eat enough to maintain your weight (eucaloric) and monitor your ketone levels to ensure you are in ketosis. This approach also appears to improve quality of life and reduce fatigue, particularly in those with overweight. You should aim for very low carbohydrate intake (around 33-35g/day) and monitor blood ketones to confirm adherence.

Combining time-restricted eating (8-hour window) with concurrent aerobic and resistance training significantly improves body weight, BMI, fat mass, and functional capacity in overweight/obese women compared to control or TRE-only groups, with no significant difference between early (4pm-8am) and late (12pm-8pm) eating windows.

To lose weight and improve fitness, combine an 8-hour eating window with 3 days per week of exercise (mix of cardio and weights). You can choose to eat early (e.g., 8am-4pm) or late (e.g., 12pm-8pm); both work equally well when you exercise. Ensure you eat enough calories (1200-1500 kcal) within that window and do not snack outside it. Consistency in both diet timing and exercise is key.

In individuals with type 2 diabetes, combining caloric restriction with high-dose exercise (300-330 minutes/week) significantly reduces fat mass percentage more than caloric restriction alone, while preserving fat-free mass.

For people with type 2 diabetes, dieting alone causes muscle loss along with fat. To maximize fat loss and keep muscle, you must add exercise. Aim for 6 sessions a week (300-330 mins total) mixing cardio and weights. If that is too much, start with 3 sessions (150-165 mins), which still burns more fat than dieting alone without losing muscle.

High-dose exercise (300-330 min/week) preserves fat-free mass during caloric restriction in type 2 diabetes, whereas moderate exercise (150-165 min/week) and diet-only interventions result in fat-free mass loss.

If you have type 2 diabetes and are dieting, you risk losing muscle. To stop this, you need high-volume exercise (at least 5 hours a week) including weights. Standard '150 minutes of exercise' guidelines are not enough to protect your muscle mass during weight loss.

Combined exercise and dietary interventions produce significantly greater body weight loss than exercise alone in adults with overweight or obesity, but do not significantly reduce ectopic fat (liver fat, visceral fat area, or intramuscular triglycerides) compared to exercise alone.

If your goal is simply to lose body weight, adding exercise to your diet will help you lose more weight than dieting alone. However, if your specific goal is to reduce ectopic fat (fat in your liver, visceral area, or muscles), simply combining diet and exercise may not be more effective than exercise alone. You may need to focus on specific types of exercise or longer durations (>12 weeks) to target these specific fat depots, as general weight loss does not guarantee ectopic fat reduction.

Long-term interventions (>12 weeks) involving either exercise or caloric restriction are successful in decreasing visceral fat area (VFA) in adults with overweight or obesity, whereas short-term interventions may not be.

To reduce visceral fat, you need to stick with your exercise or diet plan for more than 12 weeks. Short-term efforts may not be enough to target this specific type of fat. Consistency over time is key.

High-protein isocaloric diets (HPD) preserve or increase muscle mass during weight loss, whereas very low-energy diets (VLED) significantly decrease muscle mass.

If you are losing weight, ensure your protein intake is high (around 1.8g per kg of body weight). This helps you keep your muscle while losing fat. Very low-calorie diets without high protein will cause you to lose muscle mass.

Ketogenic diets (KD) significantly reduce waist circumference compared to other dietary interventions, indicating superior reduction in central adiposity.

If you want to specifically target belly fat (waist circumference), a ketogenic diet (very low carb, high fat) is effective. It significantly reduces waist size compared to other diets, even when calories are not restricted.

Isocaloric diets with macronutrient distribution (LCD, KD, HPD) result in greater weight loss than caloric restriction diets (LED, VLED) in obese women over 12 weeks.

You can lose weight without counting calories if you focus on macronutrients. Diets that adjust carbs, protein, or fat ratios (like Keto, Low-Carb, or High-Protein) can lead to greater weight loss than simple calorie restriction over 12 weeks.

A hypocaloric diet leads to statistically significant weight loss in adults with overweight or obesity regardless of whether the macronutrient composition is high-protein or high-carbohydrate.

To lose weight, you must create a caloric deficit. This study shows that whether you get those calories from protein or carbohydrates matters less than the total calorie reduction. A daily reduction of 500 kcal led to significant weight loss regardless of the macronutrient split. Choose the diet composition you can sustain best while maintaining this deficit.