Browse the evidence

Low-carbohydrate diets (LCD) and low-fat diets (LFD) produce statistically similar long-term weight loss, although LCDs yield faster initial loss.

If you are choosing between low-carb and low-fat for weight loss, expect similar results after one year. Low-carb might help you drop weight faster in the first few months, but low-fat is often easier to sustain socially and culturally. Choose the one you can stick to long-term, as the long-term weight loss difference is negligible.

Low-carbohydrate diets improve triglycerides and HDL more effectively than low-fat diets, while low-fat diets are more effective at reducing LDL cholesterol.

If your main issue is high triglycerides or low HDL, a low-carb diet may improve your heart health markers more than a low-fat diet. If your main issue is high LDL cholesterol, a low-fat diet might be more effective for that specific number. Consult a professional to interpret your full lipid panel.

Long-term adherence to a high-quality low-carbohydrate diet (HQ-LCDS) is associated with favorable changes in HDL cholesterol and triglycerides, whereas a low-quality low-carbohydrate diet (LQ-LCDS) is associated with adverse changes in fasting glucose.

If you follow a low-carbohydrate diet, ensure the carbohydrates you do eat are high-quality (high fiber, whole foods). Avoid replacing healthy carbs with refined grains or added sugars, as this can negatively impact blood glucose levels. Prioritizing high-quality carbs in your low-carb pattern improves HDL and lowers triglycerides.

High-carbohydrate diets (≥45% TDCI) are superior to low-carbohydrate diets for reducing LDL cholesterol in healthy adults under energy-matched conditions.

If your primary concern is lowering LDL cholesterol, and you are willing to eat more carbohydrates (at least 45% of your calories), this may be more effective than a low-carb diet, provided you keep your total calorie intake the same.

Low-carbohydrate diets provide short-term improvements in HbA1c and body weight but lack consistent long-term superiority over balanced diets.

Low-carb diets can be useful for short-term metabolic improvement in selected patients, but require clinical monitoring. They are not superior to balanced diets in the long term for everyone.

Low-carbohydrate diets (defined as <40% energy) improve short-term cardiovascular risk markers, specifically reducing triglycerides and increasing HDL, compared to low-fat diets, but these benefits diminish or become insignificant after 24 months.

If you switch to a low-carb diet (under 40% of calories), you will likely see improved cholesterol markers (lower triglycerides, higher HDL) and weight loss within the first 6 months. However, these specific lipid benefits tend to fade after 2 years, and LDL cholesterol might rise slightly. Because long-term adherence is difficult, consider focusing on high-quality carbohydrates (fiber, whole grains) if you cannot sustain strict low-carb intake.

High salt intake (from 2-3 sources) is significantly associated with higher odds of diabetes and overweight/obesity in older adults.

If you are over 40 and live in an urban area, reducing salt intake from multiple sources (cooking, table, snacks) can help lower your risk of diabetes and obesity. Try to limit added salt and choose less processed foods.

In women, higher intake of total protein, animal protein, polyunsaturated fatty acids (PUFA), and n-3 fatty acids is associated with decreased all-cause mortality, whereas higher carbohydrate intake is associated with increased all-cause mortality.

If you are a woman over 40, prioritizing adequate protein (especially animal sources like fish or lean meat), healthy fats (PUFA and n-3), and moderating carbohydrate intake may support longevity. If you are a man, ensuring sufficient fat intake (including saturated and monounsaturated fats) might be beneficial. These findings suggest that sex-specific dietary patterns, rather than one-size-fits-all macronutrient ratios, may be optimal for healthspan.

In men, higher intake of total fat, saturated fatty acids (SFA), monounsaturated fatty acids (MUFA), and n-6 fatty acids is associated with decreased all-cause mortality.

If you are a man over 40, ensuring adequate intake of fats, including saturated and monounsaturated fats (from sources like meat, cheese, nuts), may support longevity. This does not mean overconsumption, but rather that fat restriction may not be necessary for men in the same way it is often recommended.

Substituting 3% of total energy intake from polyunsaturated fatty acids (PUFA) for carbohydrates (low or high glycemic index) or proteins (animal or vegetable) significantly reduces systolic blood pressure (SBP) in adults.

To potentially lower systolic blood pressure, try replacing 3% of your daily calories from saturated or monounsaturated fats with Polyunsaturated Fats (PUFA). This can be done by swapping some animal proteins or refined carbohydrates for PUFA-rich foods like fatty fish, walnuts, or sunflower oil. This swap should be done while keeping your total calorie intake the same. Note that this benefit was observed in men for SBP reduction and in women for hypertension risk reduction in this specific population.

Substituting Polyunsaturated Fatty Acids (PUFA) for carbohydrates (LGI or HGI) significantly reduces the odds of developing hypertension.

To potentially lower your risk of developing hypertension, consider replacing 3% of your daily calories from carbohydrates (both low and high glycemic index) with Polyunsaturated Fats (PUFA). This is particularly beneficial for women in this study. Ensure you keep your total calorie intake the same by reducing carbs rather than adding extra fat. Good sources of PUFA include fatty fish, walnuts, and sunflower oil.

Moderate adherence to a nutrient pattern rich in unsaturated fatty acids and vitamin E is associated with lower all-cause and cancer mortality, whereas high adherence is associated with increased cerebrovascular disease mortality.

Include unsaturated fats (like those in fish and vegetable oils) and vitamin E sources in your diet, but avoid excessive consumption. The study suggests that moderate intake lowers cancer and all-cause mortality, while very high intake might increase stroke risk, possibly due to how these fats are prepared (e.g., deep-frying) or paired with other high-fat foods.

Cow milk consumption is associated with lower risk of mortality and major cardiovascular disease events, and can improve insulin resistance, particularly when derived from pasture-fed cows with higher CLA and n-3 PUFA content.

Incorporating cow milk, particularly from pasture-fed cows, can support cardiovascular health and insulin resistance. The benefits are linked to higher levels of CLA and n-3 fatty acids in pasture-fed milk. Choose high-quality dairy sources for maximum metabolic benefit.

Orlistat (60mg OTC or 120mg Rx) is a pharmacological option that reduces fat absorption but has significant gastrointestinal side effects (steatorrhea) that can be managed through patient education.

Orlistat (60mg OTC, 120mg Rx) inhibits fat absorption. It is less effective than GLP-1s. Key to adherence is educating patients to eat a low-fat diet to avoid steatorrhea. It is an adjunct to lifestyle changes.

Low-carbohydrate diets improve triglyceride levels more than balanced-carbohydrate diets in overweight/obese adults without type 2 diabetes, regardless of weight loss duration.

If you have high triglycerides, a low-carb diet may help lower them more effectively than a balanced diet, even if your weight loss is similar.

Tirzepatide treatment for obesity results in a 3:1 ratio of fat mass reduction to fat-free mass (FFM) reduction, leading to improved body composition rather than proportional lean tissue loss.

If you are using Tirzepatide for weight loss, you can expect your body composition to improve favorably. The medication targets fat stores more aggressively than lean muscle tissue, resulting in roughly three times more fat loss than muscle loss. This helps maintain your metabolic rate and physical function better than traditional caloric restriction alone, which often depletes lean mass proportionally.

Incretin-mimetic drugs (IMDs) such as semaglutide and tirzepatide cause significant skeletal muscle mass loss (≥10%) during rapid weight reduction, a loss comparable to 20 years of age-related decline.

If you are taking GLP-1 or GIP/GLP-1 drugs, expect to lose muscle along with fat. This is not just 'water weight'; it is functional tissue. To mitigate this, you must prioritize protein intake and engage in resistance training, as these are the only proven strategies to preserve muscle during rapid weight loss.

Strict weight reduction diets (Low-carb, Ketogenic, Intermittent Fasting, VLCD) significantly increase the risk of micronutrient deficiencies compared to balanced or low-fat diets.

If you use a restrictive diet like Keto or Intermittent Fasting to lose weight, you are at high risk for missing essential nutrients. You must actively supplement or carefully plan your meals to include these nutrients, as the diet itself limits your intake.

Excess caloric intake, particularly from carbohydrates (fructose/glucose) and saturated fats, drives de novo lipogenesis and hepatic fat accumulation, whereas unsaturated fats (omega-3) may reduce liver fat.

Focus on reducing added sugars (especially fructose/sweetened beverages) and saturated fats. Replace them with unsaturated fats (like omega-3s) and whole food carbohydrates. Total calories matter, but what you eat matters more for your liver.

Consuming a higher variety of protein sources (from 8 major food groups) at their respective appropriate quantity windows is inversely associated with the risk of new-onset hypertension.

To lower your risk of high blood pressure, focus on eating a wide variety of protein sources—such as grains, red meat, poultry, fish, eggs, and legumes—rather than just increasing total protein. Ensure you are eating these sources in moderate, balanced amounts, as both too little and too much of specific types can increase risk. Aim for a diverse diet that includes small portions from each of these major protein groups.

There is no single 'appropriate' amount for all protein sources; each source (red meat, poultry, fish, etc.) has a unique non-linear relationship with hypertension risk, requiring source-specific quantity windows.

Don't just focus on hitting a total protein number. Pay attention to what kind of protein you are eating. Some sources like red meat and poultry may increase risk if eaten in excess, while others like legumes and eggs may offer protection. A balanced mix of moderate amounts from various sources is key.

Adherence to a healthy low-carbohydrate diet (low low-quality carbs, high unsaturated fat, high plant protein) is associated with marginally lower total mortality (HR 0.95) in middle-aged and older adults, whereas overall or unhealthy LCDs (high saturated fat/animal protein) increase mortality risk.

If you follow a low-carbohydrate diet, prioritize unsaturated fats (like olive oil, nuts) and plant proteins (legumes, grains) while minimizing saturated fats and refined carbohydrates. Simply reducing carbs without improving food quality may increase your risk of death.

Adherence to a healthy low-fat diet (low saturated fat, high high-quality carbohydrates, high plant protein) is associated with significantly lower total (HR 0.82), cardiovascular (HR 0.84), and cancer (HR 0.82) mortality in middle-aged and older adults.

Adopt a low-fat diet that emphasizes high-quality carbohydrates (whole grains, fruits, vegetables) and plant proteins (legumes, nuts) while strictly limiting saturated fats. This pattern is associated with an 18% lower risk of death from all causes, heart disease, and cancer in older adults.

Isocaloric replacement of 3% energy from low-quality carbohydrates or saturated fat with plant protein is associated with significantly lower total, cardiovascular, and cancer mortality.

Replace 3% of your daily energy intake from refined carbohydrates and saturated fats with plant protein sources like beans, lentils, nuts, and whole grains. This simple substitution is associated with a 10% lower risk of death from all causes.