Browse the evidence

Severe caloric restriction decreases resting metabolic rate, but regular exercise can help maintain relative resting metabolic rate during such restriction.

If you are restricting calories to lose weight, incorporating regular endurance exercise can help prevent your resting metabolic rate from dropping as much as it might otherwise, particularly when measured relative to your fat-free mass.

Strength training is superior to aerobic training for reducing Body Mass Index (BMI) and body weight in overweight/obese young adults.

If you want to lower your BMI specifically, strength training might offer a slight edge over aerobic exercise, but the difference is negligible. Both are effective for weight loss.

Intermittent fasting (IF) promotes weight loss and metabolic health by inducing ketosis, improving insulin sensitivity, and regulating hunger hormones.

Try intermittent fasting, such as time-restricted eating (e.g., 16:8), to promote ketosis and regulate hunger hormones. It can be as effective as caloric restriction for weight loss.

In children, increasing intake of sugar-sweetened beverages is associated with a significantly increased risk of being overweight or obese, although intervention trials to reduce sugar intake often fail to show weight loss due to poor compliance.

For children, the strongest evidence for preventing obesity is limiting sugar-sweetened beverages. While simply telling children to cut back on sugar often fails due to poor compliance, ensuring they do not have regular access to sugary drinks significantly lowers their risk of becoming overweight (1.55x higher risk for high consumers).

In severely obese subjects, a carbohydrate-restricted diet improves insulin sensitivity independently of the amount of weight lost, compared to a low-fat diet.

For non-diabetic severely obese individuals, cutting carbs to 30g/day improves how your body handles insulin, even if you don't lose as much weight as someone on a low-fat diet. This suggests a direct metabolic benefit to carb restriction beyond just burning fewer calories.

A carbohydrate-restricted diet reduces triglyceride levels more effectively than a low-fat diet in severely obese subjects, particularly in those who lose more than 5% of their baseline weight.

If you are severely obese, a low-carb diet (≤30g/day) will lower your triglycerides much more than a low-fat diet, but this benefit is most pronounced if you actually lose more than 5% of your body weight. Simply restricting carbs without losing weight may not yield the same triglyceride benefits.

Low-carbohydrate, non-energy-restricted diets produce greater short-term weight loss (6 months) than energy-restricted low-fat diets, but this advantage disappears after 12 months.

If you are overweight, a low-carb diet where you don't count calories or restrict fat will help you lose more weight in the first 6 months than a standard low-fat, calorie-restricted diet. However, do not expect this advantage to last beyond a year; by 12 months, both groups lose roughly the same amount of weight. Focus on adherence, as the low-carb group had better completion rates initially.

Low-carbohydrate diets improve favorable cardiovascular risk markers (Triglycerides and HDL) compared to low-fat diets, but worsen LDL cholesterol levels.

If you switch to a low-carb diet, expect your HDL (good cholesterol) to go up and Triglycerides to go down, which is good. However, your LDL (bad cholesterol) may rise compared to a low-fat diet. You should monitor your full lipid panel and discuss these trade-offs with your doctor, as the net cardiovascular benefit is unclear.

In patients with diabetes, a low-carbohydrate diet improves hemoglobin A1c levels more than a conventional low-fat diet, independent of weight loss.

If you have diabetes, a very low-carbohydrate diet may help lower your average blood sugar (HbA1c) more effectively than a standard low-fat diet, even if you lose the same amount of weight. However, this benefit was observed in a smaller subgroup and requires careful monitoring.

Medically supervised very-low-calorie diet (VLCD) programs (e.g., OPTIFAST, Health Management Resources) produce significant short-term weight loss (15-25%) but are associated with high attrition and substantial long-term weight regain (maintaining only 5-9% loss at 1-4 years).

Medically supervised VLCDs like OPTIFAST or Health Management Resources can help you lose 15-25% of your body weight in 3-6 months, but they are expensive and rigid. Most people drop out, and those who finish often regain half the weight within 1-2 years unless they strictly follow a maintenance plan. Use this only if you have medical complications requiring supervision and are prepared for the cost and effort of long-term maintenance.

Weight Watchers, a nonmedical commercial program, produces modest weight loss (3.2% at 2 years) with higher adherence than self-help interventions, but evidence for other major commercial programs (Jenny Craig, LA Weight Loss) is suboptimal.

Weight Watchers can help you lose about 3% of your body weight over 2 years, which is modest but better than self-help. It works through weekly group support and behavioral counseling. It's affordable ($12/week) and accessible, making it a good choice for long-term maintenance if you value social support over rapid results.

Low-carbohydrate and low-fat diets produce statistically similar and significant weight loss in overweight and obese adults, with no clinically meaningful difference between named diet brands.

Stop searching for the single 'best' diet. Both low-carb and low-fat diets work equally well for weight loss if you stick with them. Focus on choosing a dietary pattern you can maintain for at least 6-12 months, rather than trying to outsmart the system with a specific brand or macronutrient ratio.

Low carbohydrate, low fat, and moderate macronutrient diets all produce modest weight loss and blood pressure improvements compared to usual diet at six months, but these benefits largely disappear by 12 months.

If you are overweight, switching to almost any popular named diet (low carb, low fat, or moderate) will help you lose a modest amount of weight and lower your blood pressure for the first six months. However, do not expect these benefits to persist without further intervention, as weight loss diminishes and blood pressure improvements largely disappear by the 12-month mark. The specific type of diet matters less than the initial caloric deficit and adherence.

Orlistat combined with behavioral intervention results in greater weight loss (average 3.0 kg or 6.6 lb more) than placebo plus behavioral intervention at 12 months, though with higher rates of gastrointestinal adverse effects leading to withdrawal.

Orlistat (120 mg, 3x/day) combined with behavioral counseling helps you lose about 3 kg (6.6 lbs) more than placebo over 12 months. However, be aware that gastrointestinal side effects are common and lead to higher dropout rates. Serious side effects are not increased, but the modest benefit may not be worth the side effects for everyone.

Alternate-day fasting improves cardiovascular risk markers by reducing total cholesterol, triglycerides, and LDL cholesterol, and increasing LDL particle size, though effects on HDL are inconsistent.

If you have high cholesterol or triglycerides, alternate-day fasting may help improve your numbers by lowering bad cholesterol and increasing the size of LDL particles, which is less atherogenic. Note that HDL improvements are not guaranteed.

Nutrisystem produces greater short-term weight loss (3 months) compared to control or counseling, but long-term efficacy (12 months) is unproven due to lack of long-term trials.

Nutrisystem can help you lose weight in the short term (3 months) if you are willing to use their meal replacements and attend sessions. However, there is no evidence that it works better than other methods after 12 months. If your goal is long-term weight loss, you need to find a way to maintain the habits learned during the program.

Very-low-calorie (VLC) meal replacement programs (HMR, Medifast, OPTIFAST) produce greater short-term weight loss than counseling, but effects attenuate after 6 months and carry risks of gallstones.

VLC programs like HMR, Medifast, and OPTIFAST can help you lose weight quickly (3-6 months) if you are willing to consume 800-1000 calories daily. However, the weight loss may not be sustained after 6 months, and there is a small risk of gallstones. These programs are best used under medical supervision and for short-term goals.

Atkins diet produces greater short-term weight loss than control or counseling, but long-term (12 months) efficacy is modest (0.1-2.9% greater) and similar to other diets.

The Atkins diet can help you lose weight in the short term, but its long-term (12-month) benefit is modest and similar to other diets. If you prefer a low-carbohydrate approach, it may work for you, but don't expect it to be a magic bullet. Focus on adherence and sustainable habits.

A 16-week intensive lifestyle intervention combining a hypocaloric normoproteic diet and supervised moderate exercise significantly reduces hepatic venous pressure gradient (HVPG) and body weight in patients with compensated cirrhosis and obesity, without causing clinical decompensation.

For patients with compensated cirrhosis and obesity, a structured 16-week program involving a moderate caloric deficit (500-1000 kcal/day) with adequate protein (0.8 g/kg ideal body weight) and supervised moderate exercise (60 mins/week) can safely reduce portal pressure and body weight. This approach does not appear to worsen liver function or cause decompensation, challenging the notion that such interventions are unsafe in this population.

Greater weight loss (≥10%) is associated with a greater reduction in HVPG, and higher physical activity levels (METs) are associated with greater HVPG reduction, suggesting independent benefits of weight loss and exercise on portal pressure.

While the intervention is safe for all, patients aiming for maximum portal pressure reduction should target at least 10% body weight loss and engage in higher volumes of physical activity (measured in METs), as these factors are independently associated with greater improvements in hepatic hemodynamics.

Zero-calorie alternate-day fasting (ADF) produces weight loss and metabolic improvements equivalent to moderate daily caloric restriction (CR) over 8 weeks, with a higher estimated energy deficit but similar absolute weight loss.

If you struggle with daily calorie counting, try alternating between eating normally and fasting (water/broth only) every other day. This pilot study suggests it works just as well as eating slightly less every day, without increasing the risk of regaining weight. Start with a test fast day to see if you can handle it.

Group-based support programs (Weight Watchers, Rosemary Conley) may offer better long-term adherence and less weight rebound compared to unsupported programs (Atkins, Slim-Fast) after six months.

If you find it hard to stick to a diet long-term, consider joining a group-based program (like Weight Watchers or a fitness class) rather than a self-managed book or app. The social support may help you avoid the common pattern of regaining weight after the initial 6-month success.

A five-week low-glycemic index (LGI) diet significantly reduces total fat mass and improves postprandial lipid profiles in moderately overweight nondiabetic men, despite maintaining stable body weight.

Switch to low-glycemic carbohydrates (like whole grains, legumes, and non-starchy vegetables) for five weeks. Do not try to restrict calories; keep your food intake normal. You may not see a change on the scale, but you will likely lose abdominal fat and improve your blood lipid profile due to lower insulin spikes.

VLCDs improve cardiovascular risk factors, including lowering blood pressure, serum cholesterol, and improving glucose control in type II diabetics, though HDL cholesterol may decrease in women.

VLCDs can rapidly improve blood pressure, cholesterol, and blood sugar control in obese patients with these conditions. However, women should be aware that HDL ('good') cholesterol may drop, which is a known side effect of weight loss in women.