Browse the evidence

Very-low-calorie diets (VLCDs, <800 kcal/day) significantly increase the risk of symptomatic gallstones requiring hospitalization and cholecystectomy compared to low-calorie diets (LCDs, 1200-1500 kcal/day) during commercial weight loss programs.

If you choose a very-low-calorie diet (around 500 calories/day) for rapid weight loss, be aware that your risk of developing symptomatic gallstones requiring hospital care is about three times higher than if you ate a standard low-calorie diet (1200-1500 calories). Although the absolute risk is still low, discuss this with your doctor, especially if you have other risk factors. Some studies suggest supplements like ursodeoxycholic acid might help reduce this risk.

Roux-en-Y gastric bypass surgery induces significantly higher postprandial energy expenditure and 24-hour total energy expenditure compared to vertical banded gastroplasty (VBG) in weight-stable patients, despite similar body composition and caloric intake.

This research suggests that Roux-en-Y gastric bypass surgery alters metabolism to burn more calories after meals compared to other restrictive surgeries like VBG, even when patients eat the same amount and have similar body composition. This increased energy expenditure may be a key reason why gastric bypass leads to better long-term weight loss maintenance. For non-surgical approaches, mimicking these metabolic changes (e.g., through gut hormone modulation) could be a promising strategy.

A 3-month multicomponent mobile health intervention (smartphone app + smart band + brief counseling) produces statistically significant but clinically modest weight loss and body composition improvements in overweight/obese adults compared to brief counseling alone, but these benefits are not maintained at 12 months after device removal.

Using a smartphone app and fitness tracker for 3 months can help you lose a small amount of weight and improve body composition if you are overweight or obese. However, this benefit disappears after 3 months if you stop using the devices. To maintain weight loss, you must transition the habits learned during the 3-month period (like self-monitoring and dietary awareness) into your daily life without relying on the technology.

Caloric restriction (30-40% reduction) extends mean and maximal lifespan and delays age-related diseases in nonhuman primates, suggesting similar effects in humans.

Caloric restriction of 30-40% significantly extends lifespan and reduces disease risk in primates, with strong evidence in rodents and preliminary evidence in monkeys. While likely beneficial for humans, strict adherence is difficult, suggesting a need for alternative strategies (mimetics).

Long-term energy-restricted diets for obesity result in modest, heterogeneous weight loss (approx. 3.5-4.5% at 3-4 years) with high rates of weight regain, driven by biological compensatory mechanisms.

Expect modest long-term weight loss (3-5%) rather than dramatic results. Most people will regain some weight due to biological drives (hunger, lower metabolism). Success requires accepting that maintenance is an active, ongoing biological challenge, not just a one-time diet. Focus on strategies to manage hunger and metabolic adaptation rather than expecting permanent loss from the initial diet alone.

Weight regain after initial loss is driven by a persistent reduction in total energy expenditure and an increase in hunger/satiety signals (hormonal changes).

Understand that your body fights weight loss. After losing weight, your metabolism slows and hunger hormones change permanently. This is why maintaining weight is harder than losing it. You must account for this biological shift in your long-term plan.

Very-low-energy diets (VLED) provide greater short-term weight loss than moderately energy-restricted diets, but do not yield superior long-term weight loss or maintenance.

If you need rapid weight loss for medical reasons, a VLED (<800 kcal/day) works faster than standard diets. However, do not expect it to be easier to maintain long-term. You must pair it with behavioral counseling to prevent rapid weight regain, as the long-term results are no better than standard calorie restriction.

Low-carbohydrate/high-fat diets produce greater short-to-medium term weight loss than low-fat/high-carbohydrate diets, primarily due to spontaneous energy restriction rather than a unique metabolic advantage.

Low-carb diets often lead to faster weight loss in the first 6 months because they help you eat less without counting calories. This is likely due to reduced hunger and food monotony, not a magical metabolic shift. If you prefer this way of eating, it is effective, but you must still manage your total energy intake for long-term success.

Consumption of nuts at recommended doses (approx. 28-42.5g/day) does not cause weight gain or increased adiposity in adults, and is associated with a lower incidence of overweight/obesity in long-term prospective cohorts.

You can eat nuts daily without fear of weight gain. Guidelines recommend about 1-1.5 ounces (28-42.5 grams) per day. They are high in calories but also high in fiber and protein, which helps you feel full. If you replace other snacks with nuts, you may actually lose weight or maintain it better than if you ate low-fat, high-carb snacks.

Rapid weight loss in obese women reduces resting metabolic rate (RMR) by approximately 9.4% and serum T3 by 46%, but the resulting RMR remains within the normal range of lean, non-obese individuals, meaning hypometabolism does not prevent further weight loss.

If you are struggling to lose weight on a low-calorie diet, do not assume your metabolism has slowed down so much that you cannot lose weight. Research shows that even after rapid weight loss, your metabolic rate remains within the normal range for lean people. The reason you are not losing weight is likely that you are underestimating how much you are eating, not that your body is burning too few calories.

Six months of caloric restriction (25% deficit, with or without exercise, or low-calorie diet) does not significantly increase subjective hunger or decrease fullness compared to a weight-stable control group in overweight, non-obese adults.

If you are overweight but not obese, you can lose a significant amount of weight (around 10-14%) over 6 months by eating less (25% less than your needs) without necessarily feeling much hungrier than someone who isn't dieting. This suggests that hunger is not the insurmountable barrier it is often made out to be for this population. Focus on sustainable deficit rather than fearing extreme hunger.

Ipragliflozin treatment for 24 weeks in type 2 diabetes patients reduces body weight primarily through fat mass loss while preserving total muscle mass and bone mineral content.

If you have type 2 diabetes and are already using insulin, adding 50mg of ipragliflozin daily for 24 weeks can help you lose about 2.8 kg of body weight. This weight loss comes mostly from fat, and your overall muscle mass and bone strength are likely to stay the same, which is important for maintaining strength and health.

Three weeks of 40% caloric restriction in normal-weight young men suppresses leucine flux and oxidation during exercise, yet preserves whole-body aerobic performance despite significant lean mass loss.

If you are a fit young male restricting calories by 40% for three weeks, expect to lose about 2kg of lean mass. However, your ability to perform aerobic exercise (like cycling endurance) will likely remain unchanged because your body adapts by reducing protein breakdown during activity. Do not assume performance will drop just because you are in a deficit.

Caloric restriction in normal-weight men reduces basal metabolic rate (BMR) by approximately 15% over 21 days, independent of the amount of lean mass lost.

When you restrict calories, your resting energy expenditure drops significantly (by ~15% in this study). This drop is not strictly tied to how much muscle you lose, suggesting a general metabolic slowdown to conserve energy.

A 12-week low-calorie diet inducing mild weight loss (approx. 4.8% body weight) significantly increases plasma levels of medium- and long-chain acylcarnitines (e.g., hexanoylcarnitine, octanoylcarnitine) in overweight adults, a change that negatively correlates with reductions in visceral fat area.

For overweight individuals, a sustainable, mild caloric deficit (approx. 300 kcal/day, roughly one-third of a bowl of rice per meal) sustained over 12 weeks is sufficient to reduce visceral fat and increase markers of fatty acid oxidation (acylcarnitines). You do not need extreme restriction to see metabolic benefits; consistency with a modest deficit works.

Time-restricted feeding (TRF) improves insulin sensitivity and glycemic control (including reduced glucose variability and HbA1c) in individuals with overweight or obesity, independent of significant weight loss in some studies.

If you have insulin resistance or pre-diabetes, try shifting your eating window to end earlier in the evening (e.g., 8 PM) and start later in the morning (e.g., 4 PM). This timing aligns with your body's natural circadian rhythms, helping to lower blood sugar spikes and improve how your body uses insulin, even if the scale doesn't move dramatically.

Alternate-Day Fasting (ADF) improves insulin sensitivity (HOMA-IR) more than Continuous Energy Restriction (CER).

If you are using Alternate-Day Fasting, you may see improvements in insulin sensitivity that are not seen with standard calorie restriction. This is a potential metabolic benefit of ADF.

Semaglutide and Liraglutide reduce the risk of Major Adverse Cardiovascular Events (MACEs), whereas Naltrexone/Bupropion increases the risk of elevated blood pressure.

If you have obesity and cardiovascular risks, Semaglutide or Liraglutide are preferred because they reduce MACE risk. Avoid Naltrexone/Bupropion if you have hypertension, as it increases blood pressure risk.

Negative energy balance induced by aerobic exercise or hypocaloric diet produces similar reductions in visceral adipose tissue (VAT) when weight loss is matched, regardless of exercise amount or intensity.

To reduce visceral fat, focus on creating a consistent negative energy balance. Whether you choose to do this through diet, exercise, or both, the key is the total caloric deficit. You do not need to perform high-intensity or high-volume exercise to see significant visceral fat loss; moderate-intensity aerobic exercise is equally effective. Aim for a modest weight loss (around 7%), which can yield a substantial (~25%) reduction in dangerous visceral fat.

Aerobic exercise reduces liver fat (LF) independently of weight loss, although the magnitude of reduction is modest compared to diet-induced weight loss.

Regular aerobic exercise (150-300 minutes/week) reduces liver fat, even if you don't lose weight. This is a key benefit for metabolic health. While diet-induced weight loss produces larger reductions in liver fat, exercise provides a significant independent benefit. Do not stop exercising if the scale doesn't move; your liver is still benefiting.

Three weeks of total meal replacement (TMR) at 1120 kcal/day increases dorsolateral prefrontal cortex (dlPFC) activation and enhances its inhibitory functional connectivity over the nucleus accumbens and orbitofrontal cortex in response to food cues, compared to a typical food-based diet (TD).

If you are struggling with food cravings, a short-term (3-week) period of consuming only meal replacement shakes (around 1120 calories) may help 'reset' your brain's response to food. Unlike eating normal food in portions, this approach appears to strengthen the brain's executive control centers (dlPFC) and their ability to inhibit reward centers (nucleus accumbens) when seeing food. This leads to greater weight loss and reduced cravings compared to just eating less of regular food.

Caloric restriction improves insulin sensitivity and reduces fasting insulin, but has a minor or non-significant impact on fasting glucose levels in balanced groups.

Caloric restriction lowers insulin levels, which improves insulin sensitivity. However, it may not significantly lower fasting blood glucose unless the study groups were balanced at baseline.

Time-restricted eating (TRE) significantly reduces diastolic blood pressure (DBP) in adults with obesity, but does not significantly affect systolic blood pressure (SBP).

If you have high blood pressure, TRE might help lower your diastolic (bottom) number, but don't expect it to significantly change your systolic (top) number. This is a secondary benefit to weight loss, not a primary treatment for hypertension.

High dietary fat intake promotes obesity primarily by increasing energy density and promoting passive overconsumption, while failing to stimulate compensatory fat oxidation, leading to positive energy balance in sedentary individuals.

Focus on reducing the energy density of your diet rather than just cutting fat percentages. High-fat foods are often high-calorie and low-satiety, leading to passive overconsumption. To manage weight, prioritize foods with lower energy density (high water/fiber) and ensure you are not in a caloric surplus, as your body does not efficiently burn off excess dietary fat.