Browse the evidence

A 12-week very low-calorie ketogenic diet (800-1000 kcal/day, 70% fat, 20% protein, 10% carbs) significantly reduces body weight and body fat percentage in overweight/obese adults, but also significantly decreases resting metabolic rate (RMR) and total energy expenditure.

A 12-week very low-calorie ketogenic diet (800-1000 calories, high fat) leads to significant fat loss in obese individuals, but it also significantly slows down your resting metabolism. This metabolic slowdown is a normal adaptive response to severe calorie restriction and should be expected. Long-term maintenance requires careful refeeding strategies to mitigate metabolic adaptation.

Intermittent energy restriction (IER) produces weight loss comparable to continuous energy restriction (CER) in overweight and obese adults over short-term periods (up to 12 months).

If you are overweight or obese, intermittent fasting (eating very little on 1-6 days a week) will help you lose weight just as well as eating a little less every day. It is not a magic bullet for superior weight loss, but it is a valid alternative strategy. Choose the pattern that you can stick to for at least 12 weeks.

Intermittent Caloric Restriction (ICR) helps overcome metabolic adaptation (slowed resting metabolic rate) associated with continuous caloric restriction.

If you feel your metabolism slowing down on a strict diet, try an intermittent approach (like ICR) which might help overcome metabolic adaptation.

Intermittent Fasting (IF) produces weight loss comparable to continuous caloric restriction, but is generally not recommended for Type 2 Diabetes patients due to hypoglycemia risk.

Intermittent fasting can help you lose weight just as well as counting calories every day. However, if you have Type 2 Diabetes, do not try this without a doctor's supervision due to the risk of low blood sugar.

Intermittent fasting produces weight loss equivalent to daily caloric restriction, with no statistically significant difference in efficacy between the two methods.

If you are overweight or obese, intermittent fasting is a viable weight loss strategy that works just as well as counting calories every day. You can choose a schedule that fits your life (e.g., fasting 2 days a week or eating within a 12-hour window), but expect similar results to traditional dieting. It may be preferable if you find constant daily restriction difficult to maintain.

Aerobic exercise combined with 16:8 TRE yields greater reductions in body weight and fat mass than resistance training combined with 16:8 TRE.

If you prefer resistance training, adding 16:8 TRE may still help with fat loss, but the additional benefit from TRE appears greater when combined with aerobic exercise. For maximal short-term fat loss with TRE, aerobic exercise may be the more synergistic choice.

High levels of physical activity and energy expenditure, such as those derived from cycling as daily transport, act as a protective factor against obesity, although they may be counteracted by high energy-dense diets.

Incorporate daily movement, such as cycling or walking, into your routine to support weight management. However, recognize that exercise alone may not prevent weight gain if your diet consists of energy-dense foods; you must manage both your activity levels and your caloric intake.

Alternate-day fasting (ADF) and modified fasting (e.g., 5:2 diet) result in weight loss comparable to continuous energy restriction, with mixed effects on metabolic biomarkers.

If you prefer intermittent fasting, try the 5:2 diet (eating normally 5 days, restricting calories to ~25% on 2 non-consecutive days). It leads to weight loss similar to daily calorie restriction, but may be easier to adhere to for some people. Be prepared for hunger on fasting days.

Timed food restriction or scheduled meal timing can serve as a potent non-photic zeitgeber to resynchronize peripheral clocks and improve activity rhythms in aged individuals, potentially mitigating age-associated pathologies.

Try eating your meals within a consistent daily window (e.g., 8-10 hours). This regularity acts as a strong time cue for your body's organs, helping to stabilize your sleep and metabolism, especially as you age.

Polarization of physical activity (high-intensity training combined with high sedentary time) may lead to increased health risks despite meeting physical activity recommendations.

If you do intense workouts, do not sit for the rest of the day. Break up sedentary time with light movement to avoid the health risks associated with 'polarization'.

Higher national household availability of ultra-processed foods is positively associated with higher national prevalence of obesity among adults, with each 1% increase in ultra-processed food energy share resulting in a 0.25 percentage point increase in obesity prevalence.

To reduce obesity risk, prioritize unprocessed or minimally processed foods (fruits, vegetables, meats, grains) and limit ultra-processed foods (packaged snacks, sugary drinks, ready meals). National policies should aim to make these ultra-processed options less available and affordable, as their increased presence in households correlates directly with higher obesity rates.

Quarantine leads to reduced physical activity and increased sedentary behavior, which rapidly reverses beneficial metabolic and cardiovascular adaptations, leading to insulin resistance, increased blood pressure, and higher cardiovascular risk.

Maintain physical activity through home-based exercises, online classes, or walking in small spaces. Aim to interrupt sedentary time every 30 minutes. Even short bouts of activity add up to weekly recommendations and help prevent the rapid loss of metabolic benefits.

Intermittent fasting (IF) and time-restricted feeding (TRF) reduce oxidative stress and inflammation in Type 2 Diabetes by activating AMPK and SIRT3, which promotes autophagy and mitochondrial biogenesis.

Consider time-restricted feeding by limiting your eating window to 8-10 hours per day. If using intermittent fasting, restrict energy intake by 60% on 2-3 days a week. Monitor blood glucose closely, especially if taking diabetes medication, to avoid hypoglycemia.

Reallocating time from moderate-to-vigorous physical activity (MVPA) to sedentary behavior or light physical activity (LPA) significantly increases BMI z-scores in children, whereas reallocating time to MVPA yields only modest decreases in BMI z-scores.

For children, maintaining moderate-to-vigorous physical activity (MVPA) is far more critical for weight management than simply reducing sitting time. Losing 30 minutes of MVPA has a much larger negative impact on BMI than the positive impact of gaining 30 minutes of light activity or reducing sitting. Prioritize high-intensity movement over passive rest.

The health impact of reallocating time from MVPA is greater in obese children (zBMI > 2) than in the general population, suggesting MVPA interventions are more beneficial for this subgroup.

If a child is obese, increasing MVPA is even more critical for improving BMI outcomes than for non-obese peers. The penalty for losing MVPA time is steeper in obese children, making MVPA maintenance a key focus for obesity prevention programs.

Short-chain fatty acids (SCFAs), particularly butyrate, produced by gut bacteria (e.g., Faecalibacterium, Butyricimonas) promote skeletal muscle mitochondrial biogenesis, insulin sensitivity, and prevent muscle protein catabolism.

Focus on eating prebiotic fibers (like those in onions, garlic, bananas, oats) to feed the bacteria that make butyrate. This supports your muscles' energy factories (mitochondria) and helps your body handle insulin better.

PPARβ/δ activation improves both lipid profiles and insulin sensitivity by promoting fatty acid oxidation, fiber type switching in muscle, and energy expenditure.

PPARβ/δ drugs are in development and show promise for treating both high lipids and insulin resistance by increasing energy use and improving muscle function. They are not yet available for clinical use.

Reallocating time from sedentary behavior to moderate-to-vigorous physical activity (MVPA) is associated with improvements in cardiometabolic biomarkers among adults, though evidence is lacking for children, adolescents, and older adults.

For adults, replacing sedentary time with physical activity (especially MVPA) is associated with improved cardiometabolic biomarkers. However, current evidence is insufficient to confirm these benefits for children, adolescents, and older adults.

Prolonged physical inactivity during lockdowns causes adverse metabolic and structural health changes, including insulin resistance, muscle atrophy, bone loss, and increased cardiovascular risk.

You must move to avoid health deterioration. If you cannot go outside, do indoor exercises like bodyweight squats, pushups, or stair climbing. Use resistance bands if available. Aim for moderate intensity for at least 150 minutes per week.

A pro-inflammatory diet is associated with higher risk of obesity and increased body mass index (BMI).

To manage weight, choose foods that are both anti-inflammatory and nutrient-dense. Avoid ultra-processed foods which are often high in calories and inflammatory. Focus on whole fruits, vegetables, and lean proteins.

Increased physical activity, specifically bodyweight training, during lockdown was associated with a reduced perception of weight gain.

Incorporate bodyweight training into your routine, even during lockdown. Increasing the frequency of such training (up to 5+ days/week for some) was associated with less perceived weight gain, helping to counteract the metabolic effects of reduced mobility.

Body fat percentages of 32-35% in women are associated with adverse skeletal outcomes, suggesting a lower obesity cutoff for older women than the WHO standard of 40%.

For older women, aim for a body fat percentage below 32-35% to protect bone health, rather than relying on the standard 40% cutoff.

Lower adherence to the Mediterranean Diet in women with PCOS is associated with adverse body composition, specifically lower Phase Angle (PhA) and Fat-Free Mass (FFM).

Women with PCOS often have worse body composition (lower muscle mass and cellular health, indicated by Phase Angle) than healthy women of the same weight. Improving diet quality through a Mediterranean approach may help preserve Fat-Free Mass and improve cellular health markers, even if weight loss is not the primary goal.

A Ketogenic Diet (KD) enhances endurance exercise capacity and prevents muscle injury during exhaustive exercise by altering lipid metabolism and IL-6 synthesis, though it may increase intramuscular oxidative stress.

A high-fat, low-carb diet may help endurance athletes by improving fat oxidation and preventing muscle damage, but monitor for increased oxidative stress.