Browse the evidence

Among pharmacotherapies, Semaglutide 2.4 mg and Orlistat have the most favorable safety/tolerability profiles, while Liraglutide 3.0 mg has the least tolerability, and Tirzepatide has intermediate tolerability.

When choosing a weight loss medication, be aware that tolerability varies. Semaglutide and Orlistat tend to be better tolerated, while Liraglutide may cause more side effects. Tirzepatide, despite its high efficacy, has intermediate tolerability, meaning you might experience more side effects than with Semaglutide or Orlistat.

Low-carbohydrate diets produce greater weight loss, improved HDL, and lower triglycerides compared to low-fat diets over 6-12 months, but result in higher LDL and total cholesterol levels.

If you are choosing between low-carb and low-fat for weight loss, low-carb diets tend to yield slightly better results (about 1.3 kg more loss) and improve triglycerides and HDL more effectively over 6-12 months. However, be aware that low-carb diets may raise LDL and total cholesterol. If you have high baseline LDL, a low-fat diet might be safer for your lipid profile, even if weight loss is slightly less. Monitor your lipids regardless of the diet chosen.

Improvements in insulin sensitivity (HOMA-IR) and intrahepatic lipid content during caloric restriction are transient and not maintained during the weight maintenance phase, unlike other cardiometabolic markers.

Be aware that while caloric restriction improves insulin sensitivity during the weight loss phase, this specific benefit may not persist once you stop losing weight, even if you maintain the lower calorie intake. Other cardiovascular benefits, like lower blood pressure and better cholesterol, do persist. This suggests that maintaining a healthy weight and diet is crucial, but you might need additional strategies (like exercise or specific dietary components) to sustain insulin sensitivity improvements long-term.

Weight management interventions delivered by non-medical practitioners (e.g., health coaches) are as effective as those delivered by general practitioners (GPs) or nurses.

You don't need to see a doctor for every weight management visit. Programs led by health coaches or nurses, especially when supervised by a doctor, are just as effective. Focus on finding a program with good support and regular contact.

Tirzepatide treatment in adults with obesity or overweight results in a body composition change where approximately 75% of total weight loss is fat mass and 25% is lean mass, a proportion consistent with placebo and other weight loss modalities.

If you take tirzepatide, expect to lose about 3 pounds of fat for every 1 pound of muscle. This is the same ratio you would get from dieting alone. You do not need to worry that the medication is uniquely damaging to your muscles. To protect your strength, focus on the recommended lifestyle changes: eat 500 calories less per day and move for 150 minutes a week.

Low-carbohydrate weight-reducing diets produce greater short-term weight loss (3-12 months) than balanced-carbohydrate diets in overweight/obese adults without type 2 diabetes, but this advantage disappears after 12 months.

If you want to lose weight quickly, a low-carb diet might give you a slight edge over a balanced diet in the first year. However, after a year, it offers no advantage over a balanced diet. Choose the diet you can stick to, as long-term weight loss is similar regardless of carb intake.

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.

Performing resistance training in an energy deficit impairs lean mass gains compared to training in energy balance, but does not impair strength gains.

If you are trying to lose weight while lifting weights, expect to get stronger but not necessarily bigger. A 500 kcal daily deficit will likely stop you from gaining lean mass, but you will still improve your strength. To maximize muscle growth, you must avoid prolonged energy deficits.

An energy deficit of approximately 500 kcal per day completely prevents lean mass gains from resistance training.

If your goal is to build muscle while losing fat, a 500 kcal daily deficit will likely result in zero muscle gain. You must either reduce the deficit below 500 kcal/day or accept that muscle growth will be stalled while you lose fat.

A high-intensity lifestyle intervention (ILI) delivered by health coaches in primary care significantly improves HDL cholesterol, total:HDL ratio, and metabolic syndrome severity over 24 months, but fasting glucose improvements are transient (significant at 12 months only).

If you have obesity and are seeing a primary care doctor, ask about a structured lifestyle program delivered by a health coach. This study shows that weekly visits for the first 6 months, followed by monthly check-ins, can significantly improve your 'good' cholesterol (HDL) and overall metabolic health over two years. While blood sugar improvements may fade if weight is not maintained, the lipid benefits persist.

Single-meal energy intake (EI) during ad libitum lunch meals serves as a robust short-term biomarker for predicting subsequent weight loss in adults with obesity treated with liraglutide.

For adults with obesity taking liraglutide, tracking how much you eat during a single lunch can predict your weight loss over the next few weeks. This study shows that a significant drop in lunch energy intake correlates with greater weight loss, making it a useful short-term indicator of treatment effectiveness.

Low-carbohydrate diets induce greater early-phase calorie restriction (approx. 162 kcal/d) compared to low-fat diets, but this advantage is not sustained after 3 months.

If you start a low-carb diet, expect a stronger initial drop in hunger and calorie intake compared to a low-fat diet, but don't rely on this advantage for long-term weight management. The difference disappears after 3 months, so focus on finding a sustainable way to eat that you can maintain indefinitely, regardless of the macronutrient split.

Meal replacements improve satiety and reduce cravings during caloric restriction through mechanisms like stimulus narrowing and ketosis, despite expected hormonal changes.

You might worry that eating less will make you hungry, but using meal replacements can actually help control hunger. By limiting food choices (stimulus narrowing) and potentially inducing ketosis, MRs can reduce cravings and make sticking to a diet easier.

Sustained weight loss (≥7% at 1 year) is associated with significantly lower HbA1c levels at 10 years compared to weight regain, although A1c may still rise slightly from baseline.

If you lose weight through lifestyle changes, keeping it off is crucial for long-term blood sugar control. Even if your blood sugar rises slightly from its lowest point, keeping 7% or more weight off keeps it significantly lower than if you regain the weight. This helps protect your kidneys over the next decade.

Bariatric surgery (RYGB or SG) produces significantly greater weight loss and higher treatment success rates than structured medical treatment including very low energy diet (VLED) at 2-year follow-up, though both interventions improve cardiovascular risk factors and safety profiles similarly.

For individuals with BMI ≥35, bariatric surgery (RYGB or SG) is significantly more effective than structured medical treatment (including very low energy diets) for achieving substantial weight loss and metabolic improvement at 2 years. However, medical treatment remains a viable option that yields positive cardiovascular and safety outcomes, with about 45% of patients achieving >10% weight loss. The choice involves trading the higher efficacy of surgery for the non-invasiveness of medical management.

Baseline anthropometry (initial BMI/weight) is the strongest predictor of treatment success for both surgical and medical obesity interventions, followed by psychiatric health and lifestyle factors.

Your starting weight and BMI are the best predictors of how much weight you will lose, regardless of whether you choose surgery or medical treatment. Higher baseline BMI often correlates with greater absolute weight loss. Mental health and lifestyle habits are also significant factors.

Referral to largely unsupported online weight loss programmes (NHS Weight Loss Plan, Rosemary Online, Slimming World Online) yields modest, statistically significant weight loss compared to no intervention only for Rosemary Online, while other programmes show no significant difference, indicating that digital interventions without substantial personal support are marginally superior to no intervention.

If you are considering an online weight loss program, look for one that offers some level of personal support or coaching, even if minimal. This study found that Rosemary Online, which included a proactive contact from a coach, resulted in significant weight loss compared to no intervention, whereas programs with no support (NHS Weight Loss Plan) or only chat support (Slimming World) did not show significant mean weight loss differences. Simply having access to a digital tool is not enough; engagement and support are key.

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.

Continued treatment with Tirzepatide maintains significant weight loss and cardiometabolic improvements, whereas discontinuation leads to partial weight regain and loss of benefits, demonstrating that long-term adherence is required to sustain outcomes.

If you are using Tirzepatide for weight loss, understand that it is a long-term treatment, not a short-term fix. Stopping the medication will likely cause you to regain most of the weight you lost. To keep the weight off, you must continue the medication indefinitely, combined with healthy lifestyle habits, just as you would manage high blood pressure with medication.

Short-term GPS-enabled physical activity interventions (≤3 months) produce greater weight loss effects than longer-term interventions (≥6 months).

If you start a fitness tracking program, expect the biggest results in the first 3 months. To maintain weight loss after that, you must actively work to keep the habit, as the 'newness' of the app will wear off. Consider switching to a less intrusive tracking method or adding social accountability to sustain engagement beyond the initial quarter.

Consuming two or more artificially sweetened beverages daily is associated with an elevated risk of all stroke and ischemic stroke in women.

Women should be aware that drinking two or more artificially sweetened beverages a day is linked to a higher risk of stroke. It is better to limit these drinks.

Higher diet quality attenuates the genetic predisposition for obesity, as measured by body mass index.

If you have a family history of obesity, eating a high-quality diet can help reduce the impact of your genes on your weight. Focus on the quality of your food.

Bariatric surgery reduces coronary artery disease (CAD) risk, whereas medical weight loss has not demonstrated a reduction in CAD rates.

If you have severe obesity, bariatric surgery is the only weight loss intervention proven to reduce heart disease risk. Medical weight loss programs have not shown this benefit. Discuss surgery with your doctor if you are a candidate.

Adherence to the Mediterranean Diet is associated with reduced risk of cognitive decline, dementia, and Alzheimer's disease, and improves cognitive function in older adults.

To protect your brain health as you age, follow a Mediterranean diet pattern rich in vegetables, fruits, nuts, olive oil, and fish. This way of eating has been linked to a lower risk of dementia and Alzheimer's disease and better cognitive function in older adults. It is a sustainable long-term strategy rather than a quick fix.