Browse the evidence

An 8-week sulfur amino acid restriction (SAAR) diet (~2 g/day) in humans with overweight or obesity produces significantly greater weight loss (~20% greater) compared to a control diet (~5.6 g/day), despite maintaining similar resting metabolic rates.

To lose more weight than standard dietary restriction, try reducing sulfur amino acids (methionine and cysteine) to about 2 grams per day for 8 weeks. This can be done by eating a plant-based diet and avoiding high-sulfur supplements or specific high-sulfur foods, while allowing one flexible meal a week to maintain social life. Expect roughly 20% more weight loss than a standard control diet, even if your resting metabolism doesn't change.

Metabolic adaptation (a lower-than-predicted resting metabolic rate after weight loss) significantly increases the time required to reach specific weight loss goals, independent of dietary adherence.

If you are strictly following a calorie deficit but your weight loss has stalled or slowed significantly, it may be due to metabolic adaptation (a drop in your resting metabolic rate). This is a biological defense mechanism, not a personal failure. Adjusting expectations regarding the timeline, rather than just increasing restriction, is necessary.

Fasting-based strategies (FBS) produce slightly greater short-term weight loss and fat mass reduction compared to continuous caloric restriction (CCR) in obese adults, but these differences are not clinically significant and disappear in long-term interventions (>6 months).

If your goal is weight loss, fasting strategies (like time-restricted eating) might help you lose a bit more weight and fat in the first few months compared to simply counting calories every day. However, this advantage is small (less than 1 kg) and disappears after 6 months. Since both methods result in similar long-term weight loss, choose the approach that fits your lifestyle and is easier for you to maintain consistently.

Intermittent Energy Restriction (IER) produces short-term weight loss comparable to Continuous Energy Restriction (CER), but offers no significant long-term advantages in anthropometric, cardiometabolic, inflammatory, or appetite outcomes.

If you are considering Intermittent Fasting for weight loss, expect it to work similarly to standard daily calorie restriction in the short term. Do not expect it to provide better long-term health or weight maintenance results than simply counting calories every day. The choice between IER and continuous restriction should be based on which pattern you can stick to consistently, as neither offers a long-term advantage over the other.

Static energy balance models (e.g., the 3500 kcal rule) significantly overestimate weight loss because they ignore adaptive thermogenesis, which causes resting energy expenditure to drop beyond what is explained by the loss of metabolically active tissue.

If you are dieting and hitting a plateau despite strict adherence to a calorie deficit, do not simply slash calories further. Your body has likely triggered adaptive thermogenesis, lowering your metabolic rate to protect fat stores. Recognize this as a biological defense mechanism, not a personal failure. Sustainable weight management may require longer adaptation periods or strategies that preserve fat-free mass, rather than aggressive restriction.

Metabolic adaptation (adaptive thermogenesis) is dynamic and largely reversible; it persists during negative energy balance but diminishes or disappears during weight stability or positive energy balance (refeeding).

Once you stop losing weight and reach your goal weight, your metabolic rate may partially recover if you maintain that weight. However, if you regain weight, the metabolic adaptation may return. Long-term maintenance requires accepting that your maintenance calories may be lower than before your weight loss, due to the loss of metabolically active tissue (FFM).

Intermittent Energy Restriction (IER) combined with High-Intensity Interval Training (HIIT) produces greater reductions in body weight, body fat percentage, waist circumference, and hip circumference compared to Continuous Energy Restriction (CER) combined with HIIT in overweight/obese adults, although the difference is not statistically significant in a 4-week trial.

If you are overweight or obese, combining High-Intensity Interval Training (HIIT) with an Intermittent Energy Restriction (IER) diet may help you lose more weight and body fat than a standard daily calorie-restricted diet over a short period. Specifically, eating only 30% of your daily calorie needs on two non-consecutive days a week, while eating normally on the other five days, resulted in nearly double the weight loss (4.6 kg vs 2.5 kg) compared to eating 70% of your needs every day. Although the difference wasn't statistically significant in this small 4-week study, the trend favors IER for body composition improvements.

Three-year mild caloric restriction (approx. 100 kcal/day deficit) significantly reduces plasma levels of L-leucine, L-phenylalanine, and sphingomyelin (SM d18:0/16:1) in overweight and obese middle-aged adults, independent of total weight loss magnitude.

To improve metabolic health markers like insulin sensitivity and reduce specific risk metabolites (sphingomyelin, BCAAs), aim for a modest, sustainable daily calorie deficit of about 100 calories rather than extreme restriction. This approach, maintained over years, has been shown to lower these specific blood markers more effectively than short-term extreme diets in overweight middle-aged adults.

Weight loss acts as a significant moderator for the effect of combined interventions on visceral fat area (VFA), but not for liver fat or intramuscular triglycerides (IMTG).

Losing weight helps reduce visceral fat, but it may not be enough to reduce liver or muscle fat. If you have concerns about liver or muscle fat, you may need additional strategies beyond just weight loss.

Long-term weight loss via lifestyle interventions reduces cervical subcutaneous adipose tissue (cervical-SAT) significantly, whereas chin subcutaneous adipose tissue (chin-SAT) shows a significant initial reduction but rebounds to baseline levels after 18 months.

If you are losing weight, expect your neck fat to decrease more sustainably than chin fat. While you may see an initial reduction in chin fat, it is likely to return as you maintain your weight long-term, whereas neck fat reduction is more persistent. This does not mean weight loss is ineffective, but rather that fat distribution changes are depot-specific.

Time-restricted eating (TRE) combined with caloric restriction (CR) does not yield superior weight loss compared to caloric restriction alone in overweight and obese women.

If you are already restricting calories to lose weight, adding a strict eating window may not give you any extra weight loss benefit. You can achieve similar results with just calorie control.

A 1-month very-low-calorie ketogenic diet (VLCKD) in women with obesity causes a significant reduction in 24-hour energy expenditure (24hEE) and sleeping metabolic rate (SMR), primarily driven by the loss of lean soft tissue (LST) rather than metabolic adaptation alone.

If you follow a very-low-calorie ketogenic diet, expect your daily calorie burn to drop by about 10% after a month. This isn't just 'metabolic damage'; it's largely because you are lighter and have lost some muscle. To protect your metabolism, prioritize the protein target (1.2-1.5g/kg ideal body weight) and incorporate light resistance or walking to preserve lean tissue.

Intermittent fasting (IF) produces weight loss and metabolic improvements comparable to continuous caloric restriction (CCR) in adults with overweight or obesity, without providing superior benefits.

If you are overweight or obese, intermittent fasting is a viable option for weight loss, but do not expect it to work better than simply eating fewer calories every day. Studies show that IF and continuous calorie restriction lead to similar weight loss (around 5% of body weight) and metabolic improvements over a year. Choose the method that you can stick with long-term, as adherence is key.

Lactobacillus sp. supplementation is safe and well-tolerated in non-comorbid obese individuals, with no significant adverse events reported.

You can take Lactobacillus probiotics with confidence regarding safety. Clinical trials show they are well-tolerated with no significant increase in side effects compared to a placebo.

Increasing exercise volume from 3 sessions/week to 6 sessions/week further reduces fat mass and visceral adipose tissue, although the difference in fat-free mass preservation between 3 and 6 sessions was not statistically significant for absolute fat-free mass kg.

Even 3 days of exercise per week, combined with diet, significantly improves fat loss compared to diet alone. You do not need 6 days to see benefits, but 6 days provides greater fat loss and better muscle preservation.

Higher baseline body weight and BMI strongly predict greater absolute weight loss and fat mass reduction on a very low-calorie ketogenic diet (VLCKD), with men losing significantly more weight than women.

If you have a higher starting weight, you are likely to lose more absolute weight on a VLCKD than someone with a lower starting weight. Men also tend to lose more weight than women on this specific protocol. Use your baseline weight as a predictor of success rather than comparing yourself to others with different starting points.

Flexible time-restricted eating leads to a spontaneous reduction in total energy intake without altering macronutrient composition.

If you use an 8-hour eating window, you will likely eat fewer calories without needing to count them or change your food choices. This spontaneous reduction in energy intake is a key driver of the fat loss seen with flexible TRE.

Adult humans possess functionally active brown adipose tissue (BAT) capable of thermogenesis, with prevalence inversely correlated with age, BMI, and outdoor temperature, and higher in women than men.

You likely have some active brown fat in your neck and upper chest, even as an adult. It burns calories to keep you warm, and it works best when you are younger, leaner, female, and exposed to cooler temperatures. While you can't necessarily 'train' it like a muscle, keeping your living environment moderately cool and maintaining a healthy weight may help preserve this metabolic asset.

Exposure to mild cold (16°C) activates brown adipose tissue (BAT) in healthy adult men, leading to increased energy expenditure and contributing to adaptive thermogenesis.

You likely have active brown fat, even if you are overweight. Exposing yourself to mild cold (around 60°F/16°C) for about two hours can activate this tissue and burn more calories. This is not about shivering or extreme cold, but a gentle, sustained coolness that your body can handle.

Exercise frequency positively correlates with gut microbial diversity and the abundance of beneficial bacteria (e.g., Faecalibacterium, Roseburia) that produce short-chain fatty acids (SCFAs), enhancing intestinal barrier function.

Regular physical activity boosts gut bacterial diversity and increases beneficial bacteria that produce SCFAs, which strengthen the gut barrier. Aim for daily exercise to support a healthy microbiome.

For long-term weight regulation, diet quality (types of foods) is more important than calorie counting, as different foods have divergent effects on physiological pathways of weight homeostasis.

Don't just count calories; count food types. Prioritize foods that support healthy weight regulation (vegetables, nuts, legumes, whole grains) over those that impair it (refined grains, added sugars, processed meats). This approach naturally supports long-term weight stability better than strict calorie counting.

Maintaining a body-mass index (BMI) of 25.0 to 29.9 (overweight) during midlife (age 50) is associated with a 20 to 40 percent increased risk of death from any cause, independent of smoking and preexisting chronic disease.

If you are between 50 and 71 years old, your weight at age 50 is a strong predictor of your lifespan. Being 'overweight' (BMI 25-29.9) is not harmless; it is associated with a 20-40% higher risk of dying compared to being 'normal weight' (BMI 18.5-24.9). If you are currently overweight, focusing on gradual weight loss to reach the normal range is one of the most impactful actions you can take for longevity, especially if you have never smoked.

Obesity is a more prominent risk factor for developing type 2 diabetes in women than in men, with a stronger association between increasing BMI and diabetes risk observed in females.

For women, maintaining a healthy weight is critically important for preventing type 2 diabetes, potentially more so than for men of the same BMI. Weight management strategies should be prioritized, as the link between excess weight and diabetes risk is stronger in females.

Visceral adipose tissue (VAT) is a stronger predictor of cardiometabolic risk in men, whereas the ratio of visceral to subcutaneous fat (VAT/SAT) is a stronger predictor in women.

When assessing diabetes risk, men should be evaluated based on visceral fat levels, while women should be evaluated based on the ratio of visceral to subcutaneous fat. This sex-specific approach may improve risk prediction accuracy.