updated by Prof. Gabriele Riccardi, August 2021
Obesity is a serious chronic disease of epidemic and global proportions; especially when body fat is predominantly visceral, it is often associated with cardiovascular risk factors, such as dyslipidemia (high triglycerides, low HDL cholesterol, and abnormal LDL composition, i.e. presence of small, dense LDL particles), hypertension and left ventricular hypertrophy and impaired glucose tolerance/diabetes.
The incidence of cardiovascular events is increased in people with cardiovascular disease who are obese or overweight, although there is insufficient evidence as to whether weight reduction decreases cardiovascular mortality in this group of patients. However, a systematic review and meta-analysis of randomized controlled trials (RCTs) shows that weight reducing diets for adults with obesity, usually low in fat and low in saturated fat, were associated with a 18% relative reduction in premature mortality over a median trial duration of two years, corresponding to six fewer deaths per 1000 participants (95% confidence interval two to 10). The evidence on cardiovascular mortality, or participants developing cardiovascular events is not clearly in support of a beneficial effect, probably due to a low number of events.
The presence of abdominal adiposity and metabolic syndrome increases the cardiovascular benefits of weight reducing regimens, which are, therefore, particularly indicated when these conditions are identified. The therapeutic approaches for obesity are lifestyle changes, drug treatment and bariatric surgery.
Lifestyle changes, focused on a modest (5-10%) weight loss and moderate- high intensity physical activity, can significantly reduce the cardiometabolic risk factors. A low-fat (low saturated fat) diet, rich in fruit and vegetables, as well as legumes and whole grains, and low in sugar, should be advised to overweight people for its beneficial impact on weight and cardiovascular risk. Low and very low (ketogenic) carbohydrate diets have become very popular in recent times; however, while they are very effective on weight reduction in the short term, their effects usually vanish after one or two years. Moreover, the available evidence shows mixed effects of these diets on low-density lipoprotein cholesterol levels with some studies showing an increase.
The two main weight-reducing drugs currently available are phentermine-topiramate and liraglutide or semaglutide. Bariatric surgery represents an effective treatment in case of severe obesity for its beneficial impact on survival, cardiovascular risk factors, prevention/remission of chronic diseases (hypertension, hyperlipidemia and diabetes), cardiovascular events and mortality.
Measurements and goals
- Measurements of Body Mass Index (BMI) and waist circumference are recommended at each office visit, followed by objective feedback and consistent counselling on weight loss strategies. BMI is calculated using the formula weight (kg)/height (m)2. If the patient is overweight (BMI>25 kg/m2),weight loss is indicated. Waist circumference is measured with a tape at the end of a normal expiration, with the arms relaxed at the sides, below the midline of the participant's armpit, at the midpoint between the lower part of the last rib and the top of the hip. Waist circumference values should not exceed 94 cm in males and 80 cm in females.
- Treatment goal : 5-10% weight loss
- Weight reduction can be achieved by decreasing the consumption of energy-dense foods (high fat, high sugar, refined cereals, alcohol) inducing a caloric deficit of 300–500 kcal/day. To be effective in the long run, this advice should be incorporated into structured, intensive lifestyle education programmes. To help maintain a body weight close to the target, it is always appropriate to advise people who are overweight or obese to engage in regular physical exercise of moderate intensity
- General recommendations for a healthy diet:
- Limit energy intake from total fat
- Replace saturated fats (mostly of animal origin) with unsaturated fats
- Increase consumption of fruit, vegetables, and legumes
- Reduce the intake of refined starchy foods (to be partially replaced by whole grains) and sugars (particularly in beverages)
- Physical exercise: please see the Physical exercise page for detailed recommendations.
- Alcohol consumption should be drastically limited, considering its energy content. Example of on-line calorie calculators are shown below:
Among overweight or obese adults, orlistat, lorcaserin, naltrexone-bupropion, phentermine-topiramate, and liraglutide, compared with placebo, are associated with achieving at least 5% weight loss after 52 weeks of treatment. Phentermine-topiramate (phentermine acts as an appetite suppressant via the central nervous system; topiramate decreases the appetite) and liraglutide or semaglutide (analogues of human GLP-1 that acts as a GLP-1 receptor agonist; they reduce hunger and decrease food intake) are associated with the highest odds of achieving at least 5% weight loss.
- Indications for surgery: for people with a BMI >40; a lower cut-off may be appropriate if the patient suffers from certain comorbidities (like type 2 diabetes or metabolic syndrome): BMI > 35 or even > 30, if blood glucose levels are not adequately controlled.
- Disadvantages of bariatric surgery: bariatric surgery is, by definition, invasive and has inherent short-term risks (surgical complications) as well as adverse effects that may become apparent only during a longer term follow-up. Deficiencies of Vitamin B12 and iron are relatively frequent; other less common nutritional deficiencies are related to copper, calcium, zinc Vitamin D, and folate.
Nutritional supplements are needed. Long-term medical and nutritional follow-up is usually appropriate
Table 1. Diagnosis of the metabolic syndrome (in the presence of three or more of the following criteria)
|Components of metabolic syndrome||ATP III definition|
|Waist circumference||Men: > 102 cm
Women: > 88 cm
|Triglycerides||≥ 150 mg/dl|
|HDL-cholesterol||Men: < 40 mg/dl
Women: < 50 mg/dl
|Systolic/diastolic blood pressure||≥ 130/≥ 85 mmHg or antihypertensive drugs|
|Fasting glycaemia||≥ 100 mg/dl or antihyperglycaemic drugs|
Table 2. A guide to deciding the initial level of intervention to discuss with the patient
|25.0 - 29.9||L||L||L ± D|
|30.0 - 34.9||L||L ± D||L ± D ± S**|
|35.0 - 39.9||L ± D||L ± D||L ± D ± S|
|≥40||L ± D ± S||L ± D ± S||L ± D ± S|
L: Lifestyle intervention (diet and physical activity); D: consider drugs; S: consider surgery.
*BMI and waist circumference cut-off points are different for some ethnic groups.
** Patients with type 2 diabetes on individual basis.
Yumuk V et al, European Guidelines for Obesity management in Adults. Obes Facts 2015;8:402-424 (5)
How to achieve optimum target weight: moving from a lower to a higher level if the target is not achieved
- Lifestyle: reinforcement of healthy eating and physical activity messages (GP, nurse)
- Lifestyle: community-based diet, nutrition, lifestyle and behavioural change advice, normally in a group setting (local community weight management services)
- Lifestyle + drugs: multidisciplinary team approach led by an obesity specialist; the use of weight reducing drugs (phentermine-topiramate, liraglutide or semaglutide) is considered (GP, specialist nurse, specialist dietitian, psychologist, psychiatrist, and physiotherapist)
- Bariatric surgery (if indicated, see Table 2): multidisciplinary team before and after surgery