Browse the evidence

Pharmacotherapy (sibutramine, orlistat) is effective for weight loss only when used in combination with lifestyle modifications (diet and exercise).

If you meet the medical criteria (BMI >=30 or >=27 with comorbidities), medications like sibutramine or orlistat can help. However, they are not magic bullets. They work best when you also make changes to your diet and exercise habits. Consult a physician to determine if pharmacotherapy is appropriate for you.

Large, intentional weight loss induced by bariatric surgery significantly reduces the 2-year incidence of hypertension, diabetes, hyperinsulinemia, and lipid disturbances in severely obese individuals compared to matched controls.

For severely obese individuals, bariatric surgery is a highly effective intervention for preventing the onset of type 2 diabetes, hypertension, and lipid disorders over a 2-year period. The key is achieving large, sustained weight loss, which surgery facilitates more reliably than conventional treatments.

A maintained weight reduction of approximately 9% or more after one year is sufficient to significantly decrease the 2-year incidence of diabetes, hyperinsulinemia, hypertriglyceridemia, and hypo-HDL-cholesterolemia, while a 30% reduction is required for hypertension.

You do not need to lose a massive amount of weight to see metabolic benefits. Losing just 9% of your body weight can significantly lower your risk of diabetes and lipid issues. However, preventing high blood pressure may require a larger loss (around 30%).

Regular moderate-intensity exercise (approx. 200 min/week) significantly reduces total body fat and intra-abdominal fat in sedentary, overweight postmenopausal women without caloric restriction.

To lose body fat, aim for about 3.5 days of moderate exercise per week, totaling around 200 minutes. You do not need to change your diet to see results, though maintaining your usual intake is key. Start with shorter, easier sessions and gradually increase the duration and intensity over the first two months to build consistency.

Combining diet with exercise yields significantly greater long-term weight loss (approx. 1.14 kg) compared to diet alone in overweight or obese adults.

If you are trying to lose weight long-term, adding exercise to your diet will help you lose more weight than dieting alone. While the average extra loss is about 1.1 kg (2.5 lbs), this benefit persists even after 2 years. You do not need a specific type of exercise or diet; the combination itself is the key factor for superior outcomes compared to diet restriction alone.

Intermittent energy and carbohydrate restriction (IECR) performed on 2 days per week yields significantly greater reductions in insulin resistance (HOMA) and body fat compared to daily energy restriction (DER) in overweight women over a 3-month period.

To improve insulin sensitivity and lose more body fat than standard daily dieting, try restricting calories and carbs to very low levels (under 40g carbs, ~600 kcal) for just 2 consecutive days a week. On the other 5 days, eat enough to maintain your weight using a balanced, Mediterranean-style diet. This approach was shown to be more effective for metabolic health and fat loss than restricting calories every single day for 3 months.

Moderate caloric restriction (1200-1500 kcal/d) combined with behavior modification produces an average short-term weight loss of 8.5 kg over 20 weeks, though patients typically regain one-third of this loss within one year.

To lose weight using moderate restriction, aim for 1200-1500 calories daily with a focus on behavior change (tracking food/activity). Expect to lose about 8.5 kg in 5 months. To keep it off, you must treat obesity as a chronic condition and engage in ongoing maintenance, such as regular check-ins or exercise, rather than stopping after the initial loss.

Continuing care (maintenance therapy) and regular exercise significantly improve the long-term maintenance of weight loss after both moderate and severe caloric restriction.

To keep weight off, you must continue the effort. Join a maintenance program or exercise regularly. Stopping after the initial loss usually leads to regain because obesity is a chronic condition.

Low-carbohydrate diets (≤45% energy from carbs) are at least as effective as low-fat diets (≤30% energy from fat) for reducing body weight and waist circumference over interventions of 6 months or longer.

If you are overweight or obese, switching to a low-carbohydrate diet (limiting carbs to 45% of calories or less) will likely result in similar weight loss to a low-fat diet over the long term (6+ months). You do not need to restrict calories more strictly than a low-fat dieter; simply shifting macronutrient ratios is sufficient to achieve comparable weight reduction.

Increasing physical activity energy expenditure (PAEE) over time significantly reduces all-cause, cardiovascular, and cancer mortality in middle-aged and older adults, regardless of their baseline activity levels or existing medical history.

If you are currently inactive, gradually increasing your physical activity over time—aiming to reach at least 150 minutes of moderate activity per week—will significantly lower your risk of dying from any cause, heart disease, or cancer. This benefit applies even if you have existing health conditions like heart disease or cancer, and it does not matter how inactive you were in the past; the act of increasing your activity is what drives the longevity gain.

Maintaining or increasing physical activity to meet or exceed WHO minimum guidelines (150 min/week) at the population level could prevent 46% of deaths associated with physical inactivity.

To maximize your population-level impact and personal longevity, aim to consistently meet the standard recommendation of 150 minutes of moderate-intensity activity per week. You do not need to exceed this significantly to prevent nearly half of the deaths linked to inactivity; consistency at this level is highly effective.

Low-carbohydrate/high-protein (LC/HP) diets produce significantly greater short-term weight loss (6 months) compared to low-fat/low-calorie (LF/HC) diets, although this advantage diminishes by 12 months.

If you are obese (BMI 28+), a low-carbohydrate, high-protein diet is likely to help you lose more weight in the first 6 months than a standard low-fat, calorie-restricted diet. While the difference narrows by 12 months, the initial advantage and higher adherence (lower dropout) make LC/HP a strong first-line strategy for rapid weight reduction.

Behaviorally based weight-loss interventions result in statistically significant weight loss (average 3.0 kg or 6.6 lb greater than control) at 12 to 18 months, with greater intervention intensity (12-26 sessions) yielding greater loss (4-7 kg).

To lose weight using behavioral methods, you need to commit to a structured program with frequent contact (12-26 sessions in the first year). Expect to lose about 4-7 kg (9-15 lbs) if you attend these sessions, which is significantly more than doing nothing. Less intensive programs (<12 sessions) result in much smaller losses (1.5-4 kg).

Behavioral interventions, orlistat, and metformin all reduce diabetes incidence in patients with prediabetes or elevated risk, with behavioral interventions cutting incidence by about 50% or more over 2-3 years.

If you have prediabetes, behavioral weight loss programs can cut your risk of developing type 2 diabetes by half or more over 2-3 years. Orlistat and metformin also reduce risk, but behavioral interventions are the most robustly supported for this outcome.

Sustaining a weight loss of 10% or more of initial body weight over 24 months requires maintaining leisure-time physical activity (LTPA) of approximately 275 minutes per week (or ~1800 kcal/week), which is roughly double the standard public health recommendation of 150 minutes per week.

If your goal is to keep off more than 10% of your body weight long-term, standard exercise guidelines (150 minutes/week) are likely insufficient. You need to aim for roughly 275 minutes of moderate-to-vigorous activity per week (about 55 minutes, 5 days a week). This is double the standard recommendation. Combine this with a caloric deficit and behavioral support (like regular check-ins) to maximize your chances of success.

A whole food plant-based (WFPB) diet, specifically low in fat (7-15% energy) and ad libitum (no calorie restriction), produces significant weight loss and BMI reduction in adults with obesity, type 2 diabetes, or cardiovascular risk factors, superior to standard care alone.

Adopt a whole food, plant-based diet that is low in fat (minimize oils, nuts, avocados) and high in starches (potatoes, bread, pasta, rice) and vegetables. Do not count calories; eat until you are full. Take a 50 mcg daily Vitamin B12 supplement. This approach has been shown to produce significant weight loss and improve metabolic markers in people with obesity and related conditions, without needing to restrict total energy intake or exercise.

A high-carbohydrate, low-glycemic index (GI) diet optimizes both body fat loss and cardiovascular risk reduction (specifically LDL cholesterol) compared to high-protein or high-GI diets in overweight young adults.

To maximize fat loss and improve your cholesterol, focus on high-carbohydrate foods that have a low glycemic index (like legumes, whole grains, and non-starchy vegetables) rather than just cutting carbs or increasing protein. This approach helps manage blood sugar and insulin, which drives fat storage, while simultaneously lowering LDL cholesterol.

Lowering the Glycemic Index (GI) of a high-carbohydrate diet doubles fat loss in women compared to a high-GI high-carbohydrate diet, without compromising lean mass.

If you prefer eating carbohydrates, choose low-GI options like legumes, whole grains, and non-starchy vegetables. This strategy can double your fat loss compared to eating high-GI carbohydrates, while preserving your muscle mass.

Combining calorie-restricted diets with regular physical exercise produces superior and more sustainable weight loss compared to diet or exercise alone.

To lose weight and keep it off, you must combine a reduced-calorie diet with regular exercise. Aim for a 500-1000 kcal daily deficit and 200-300 minutes of moderate exercise per week. Don't rely on exercise alone for initial loss; use it to help you stick to your diet and maintain your weight long-term. Choose a diet style you enjoy to ensure compliance.

Improving fitness from an 'unfit' status (<5 METs) to a 'fit' status (>5 METs) significantly reduces mortality risk, even in older adults.

If you are an older man with low fitness, you can significantly lower your risk of death by improving your physical capacity. You do not need to reach elite levels; simply moving from a low fitness level (below 5 METs) to a moderate level (above 5 METs) can reduce your mortality risk by 35%. This improvement can be achieved through regular, moderate-intensity physical activity.

Aerobic exercise performed at moderate to high intensity reduces visceral adipose tissue (VAT) in overweight and obese adults, even without caloric restriction.

To reduce dangerous belly fat (visceral adipose tissue), focus on aerobic exercises like brisk walking, jogging, or cycling at a moderate to high intensity (where you can talk but not sing, or higher). Do this at least twice a week for at least 8 weeks. You do not need to restrict calories to see these specific fat loss benefits, though diet is still important for overall health. Men tend to see slightly larger reductions in visceral fat area than women with this approach.

Adherence to a low-carbohydrate diet (LCD) in obese adults results in significant, sustained reductions in body weight, BMI, abdominal circumference, systolic and diastolic blood pressure, fasting triglycerides, fasting glucose, glycated hemoglobin, and insulin, alongside a significant increase in HDL cholesterol.

If you are obese and follow a low-carbohydrate diet, you can expect significant weight loss (average ~7kg) and improvements in blood pressure, blood sugar, and triglycerides. The specific carbohydrate limit varies by study (some <30g, some <40% of calories), but the trend holds across these variations. You do not need to strictly limit fat intake to see these benefits, as triglycerides tend to drop regardless.

Sustained moderate-intensity aerobic exercise combined with constant energy intake induces significant fat mass loss while completely preserving fat-free mass.

To lose fat without losing muscle, you must exercise moderately (around 50-55% of your max effort) for about 93 days, burning roughly 1,000 kcal daily through exercise, while eating exactly enough to maintain your current weight. Do not restrict calories; let the exercise create the deficit. This preserves your lean mass while stripping fat.

Diet-induced weight loss significantly improves coronary artery disease (CAD) risk factors (glucose, insulin, lipids, blood pressure) in obese, middle-aged and older men, whereas aerobic exercise training without weight loss has substantially less beneficial effects on these parameters.

If you are obese and middle-aged or older, losing weight through diet is significantly more effective for improving your blood sugar, cholesterol, and blood pressure than exercising alone. While exercise is great for heart fitness, it does not fix metabolic issues as well as shedding fat mass. Focus on creating a caloric deficit to reduce body weight by at least 10%.