Browse the evidence

The thermic effect of food (TEF) varies significantly by macronutrient composition, with protein eliciting a thermic effect at least three times higher than isocaloric carbohydrates, while fat elicits a much lower thermic effect.

Eating protein costs more energy to digest than carbs or fat. Prioritizing protein in your diet can slightly increase your daily energy expenditure through the thermic effect of food.

Switching from saturated and trans fats to unsaturated fats (MUFAs and PUFAs) in the diet causally reduces plasma LDL particle concentration, thereby reducing the risk of atherosclerotic cardiovascular disease (ASCVD).

To lower your risk of heart disease, focus on swapping the types of fat you eat. Replace saturated fats (found in butter, fatty meats, full-fat dairy) and trans fats with unsaturated fats (found in olive oil, nuts, seeds, and fatty fish). This substitution lowers LDL cholesterol, which is a primary driver of heart disease. You don't need to eliminate fat; just choose higher-quality sources.

Trans fats are harmful and should be eliminated, while saturated fat's impact depends on the food matrix and what it replaces.

Eliminate trans fats completely. For saturated fats, focus on the food source (e.g., cheese, nuts) rather than just the fat content, and ensure you are replacing them with unsaturated fats, not refined carbs.

Carbohydrate-restricted diets (≤45% energy) significantly improve cardiovascular health by reducing triglycerides, blood pressure, and inflammatory markers, despite modest increases in LDL and total cholesterol.

Adopting a diet with less than 45% of calories from carbs improves heart health markers like blood pressure and triglycerides. Even if your LDL cholesterol rises slightly, your overall cardiovascular risk likely decreases because your triglycerides drop, inflammation goes down, and your cholesterol ratios improve. This is especially true if you replace carbs with a mix of fats and proteins.

Adherence to a low-carbohydrate diet (LCD) results in significantly greater reductions in body mass index (BMI), total body weight, and body fat percentage compared to a low-fat diet (LFD).

If you are trying to lose weight, a low-carbohydrate diet (30-130g carbs/day) is likely to produce slightly better results in BMI, total weight, and body fat percentage than a low-fat diet. This holds true across various populations, including those with type 2 diabetes or metabolic syndrome. Note that the absolute difference in fat mass (kg) and waist circumference was not significantly different between the two diets in the overall analysis.

Replacing dietary saturated fat with polyunsaturated vegetable oils significantly reduces cardiovascular disease incidence by approximately 30%, an effect comparable to statin treatment.

To lower your risk of heart disease, swap foods high in saturated fats (like butter, lard, and fatty meats) for foods high in polyunsaturated fats (like corn, soybean, and safflower oils). Do not replace these fats with refined carbs or sugars, as that offers no heart benefit. This change should be part of an overall healthy diet like the Mediterranean diet.

Adopting energy-balanced, predominantly plant-based dietary patterns (flexitarian, pescatarian, vegetarian, or vegan) significantly reduces premature mortality by 19-22% and greenhouse gas emissions by 54-87% compared to current global diets.

To improve your health and reduce your environmental footprint, shift your diet towards being predominantly plant-based while maintaining energy balance. Focus on increasing intake of fruits, vegetables, legumes, and nuts. If you eat meat, choose fish or poultry in moderation, and avoid processed meats. This approach is adaptable to your local food culture and has been shown to significantly reduce the risk of premature death from chronic diseases.

For healthy, exercising individuals, an overall daily protein intake of 1.4–2.0 g/kg body weight per day is sufficient to build and maintain muscle mass, with higher intakes (2.3–3.1 g/kg/d) only necessary during hypocaloric periods to maximize lean body mass retention.

Aim for 1.4 to 2.0 grams of protein per kilogram of body weight every day if you are training. If you are cutting calories to lose fat, bump this up to 2.3–3.1 grams per kilogram to protect your muscle. You do not need to exceed these amounts for muscle growth in a caloric surplus.

Low consumption of whole grains is a convincing risk factor for increased Type 2 Diabetes Mellitus (T2DM) incidence.

Increasing your intake of whole grains is a highly effective strategy to reduce your risk of Type 2 Diabetes. The evidence is very strong: people who eat more whole grains have a significantly lower risk of developing the disease. Prioritize whole grains over refined grains.

High consumption of sugar-sweetened beverages is a convincing risk factor for increased Type 2 Diabetes Mellitus (T2DM) incidence.

Reducing your intake of sugar-sweetened beverages is a highly effective strategy to reduce your risk of Type 2 Diabetes. The evidence is very strong: people who drink more sugar-sweetened beverages have a significantly higher risk of developing the disease. Consider replacing these with water or unsweetened beverages.

Low adherence to a healthy dietary pattern is a convincing risk factor for increased Type 2 Diabetes Mellitus (T2DM) incidence.

Adhering to a healthy dietary pattern is a highly effective strategy to reduce your risk of Type 2 Diabetes. The evidence is very strong: people who follow a healthy dietary pattern have a significantly lower risk of developing the disease. Focus on whole foods, fruits, vegetables, and whole grains, and limit processed foods.

US adults significantly improved diet quality between 1999 and 2016 by decreasing low-quality carbohydrates (primarily added sugars) and increasing high-quality carbohydrates (primarily whole grains), plant protein, and polyunsaturated fats.

Focus on swapping low-quality carbohydrates for high-quality ones. Specifically, reduce added sugars and increase intake of whole grains, plant-based proteins (like nuts and whole grains), and polyunsaturated fats. While overall diet quality has improved, these specific swaps are the key drivers of that improvement.

An isocaloric Mediterranean diet intervention significantly lowers total, LDL, and HDL plasma cholesterol in overweight and obese adults within 4 weeks, independent of energy intake or physical activity changes.

If you are overweight or obese, switching to a Mediterranean dietary pattern can lower your total and LDL cholesterol within just 4 weeks, even if you do not lose weight or change your exercise habits. Focus on replacing meat and refined cereals with fruits, vegetables, whole grains, legumes, and nuts. The greater your adherence to this pattern, the more your cholesterol drops.

Macronutrient composition (low-carb vs. low-fat) has no significant difference on weight loss outcomes when total caloric intake and adherence are controlled.

Don't obsess over whether you should be low-carb or low-fat. The most important factor is that you eat fewer calories than you burn. You can achieve this with almost any dietary pattern (Mediterranean, low-carb, low-fat) as long as you stick to it and maintain a calorie deficit.

High-fat and fasting diets increase lipid oxidation (LIPOX) and lower respiratory quotient (RQ), which is directly associated with increased circulating acylcarnitines and decreased glycerophospholipids, indicating a coordinated metabolic shift toward mitochondrial beta-oxidation.

When you eat a high-fat or fasted state, your body shifts to burning fat for fuel. This shift is measurable through specific blood markers (acylcarnitines) and breathing ratios (RQ). If you want to increase fat oxidation, reducing carbohydrate intake or fasting are effective strategies.

Macronutrient composition (carbohydrate vs fat vs protein ratios) does not significantly impact weight loss outcomes when total caloric intake is controlled, provided the diet is sustainable.

You do not need to follow a specific 'low-carb' or 'low-fat' diet to lose weight. Studies show that when calories are equal, the source of those calories (carbs vs fat vs protein) matters less for weight loss than the total amount. Focus on finding a dietary pattern you enjoy and can stick with long-term.

There is no universally superior diet (low-carb vs. low-fat) for long-term weight loss; both result in similar energy intake and weight loss outcomes when protein and calories are controlled.

Don't obsess over whether to cut carbs or fat. Both approaches work equally well for weight loss if you maintain a calorie deficit. Choose the dietary pattern that fits your lifestyle, preferences, and health markers (like blood sugar) best, as no single diet is superior for everyone.

Higher circulating and tissue levels of linoleic acid (LA), the primary dietary omega-6 fatty acid, are associated with a significantly lower risk of total cardiovascular disease, cardiovascular mortality, and ischemic stroke.

Focus on maintaining healthy levels of linoleic acid (LA) through your diet, as higher biomarker levels of LA are linked to lower risks of heart disease and stroke. This suggests that current dietary guidelines recommending omega-6 intake are supported by large-scale evidence, and you do not need to fear omega-6 fatty acids for causing heart disease.

A Mediterranean diet supplemented with extra virgin olive oil or nuts mitigates the deleterious effect of elevated plasma ceramide concentrations on cardiovascular disease risk, effectively neutralizing the increased risk associated with high ceramide levels.

If you have high ceramide levels, switching to a Mediterranean diet rich in olive oil or nuts can effectively cancel out the increased heart disease risk associated with those levels. This dietary pattern brings your risk down to the same level as people with naturally low ceramide levels.

Ketogenic diets (≤10% carbs) produce greater weight loss but also greater increases in LDL and total cholesterol compared to moderate-carb diets (26-45% carbs).

If you choose a strict ketogenic diet (under 10% carbs), expect greater weight loss but also a significant rise in LDL and total cholesterol. If you want a balance of weight loss and heart health markers, a moderate-carb diet (26-45% carbs) might be a better choice.

A 12-month healthy low-carbohydrate diet and a healthy low-fat diet produce statistically equivalent weight loss in overweight adults, with no significant difference between the two approaches.

For overweight adults, both a healthy low-fat diet and a healthy low-carbohydrate diet lead to similar weight loss over 12 months. The specific macronutrient ratio matters less than the quality of food (whole foods, minimal processing) and the ability to adhere to the diet long-term. You do not need genetic testing or insulin measurements to choose between them; pick the one you can sustain.

Low carbohydrate diets are not significantly superior to low fat diets for weight loss when protein content is held constant.

You do not need to choose between low-carb and low-fat based on efficacy; both work equally well if you stick to them. Focus on adherence and protein intake rather than eliminating entire food groups, as no single diet is superior.

Ad libitum low-carbohydrate diets promote weight loss without significant fat mass reduction, whereas ad libitum low-fat diets promote significant fat mass loss, indicating that early weight loss on low-carb diets does not necessarily reflect negative energy balance or fat loss.

If your goal is fat loss, a low-fat diet may be more effective than a low-carb diet when eating ad libitum, as low-carb diets may result in weight loss driven by water and glycogen depletion rather than fat loss. Focus on body composition changes (like DEXA scans or progress photos) rather than just scale weight when starting a low-carb diet.

There is no significant difference in the reduction of absolute fat mass (kg) or waist circumference between low-carbohydrate and low-fat diets.

While LCDs may lower BMI and body fat percentage more than LFDs, they do not necessarily reduce absolute fat mass (kg) or waist circumference more effectively. If waist circumference is your primary goal, either diet may be equally effective.