How to reduce a big belly? What are the dangers? AHA scientific statement

Since the 1980s, the prevalence of obesity has been rising in most countries around the world. According to the Global Burden of Disease Study, 600 million people are obese worldwide. Between 39% and 49% of the world's population (2.8 billion to 3.5 billion people) are overweight or obese. From 1980 to 2015, the prevalence of obesity doubled in 73 countries.

Obesity can lead to dyslipidemia, type 2 diabetes, hypertension, etc., increasing the risk of cardiovascular disease and death. In 2015, high body mass index caused 4 million deaths, more than two-thirds of which were caused by cardiovascular disease.

Recently, the American Heart Association (AHA) issued a scientific statement on obesity and cardiovascular disease, pointing out that obesity is a complex chronic disease and a multifactorial disease. Biological, environmental, psychosocial and other multi-level factors jointly contribute to obesity.

The statement pointed out that excessive visceral fat is an independent indicator of adverse cardiovascular prognosis. Obesity leads to cardiovascular complications, which is not only related to the amount of body fat, but also depends to a large extent on the distribution of fat.

Imaging studies have shown that in patients with visceral obesity, the most common is liver fat accumulation, manifested as non-alcoholic fatty liver disease.

The guidelines believe that abdominal obesity, as measured by waist circumference, is a risk marker for cardiovascular disease.

Waist circumference exceeds half of height, higher risk of cardiovascular disease

Regarding obesity assessment indicators, although waist circumference is the main indicator for assessing abdominal obesity, considering body size, waist circumference/height as an indicator of obesity may be a better indicator for predicting cardiovascular disease.

The PURE-China research team found that if the body grows horizontally and the waist circumference exceeds half of the height, there is a possibility of metabolic problems such as dyslipidemia and hyperglycemia, and the risk of cardiovascular disease is also higher.

In addition, waist-to-hip ratio (WHR) has been shown to predict cardiovascular mortality independently of BMI. Obesity assessed by waist circumference and WHR has been shown to be a cardiovascular disease factor independent of BMI.

Exercise can reduce visceral fat, even without changing weight

Physical activity, or physical activity interventions combined with diet, has been shown to reduce visceral, pericardial, and epicardial fat.

Randomized studies in men and women of different ages found that exercising 3 to 5 times per week for 12 to 52 weeks reduced visceral fat compared with a non-exercise control group.

Exercise can reduce visceral fat even without weight loss. A meta-analysis reported that exercise can reduce visceral fat by 6.1% in the absence of weight loss.

In the absence of weight loss, visceral fat decreases, which may be related to increases in muscle mass.

The statement pointed out that reducing calories can also reduce abdominal fat. However, compared with dietary intervention, most studies show that exercise is more beneficial in reducing visceral fat.

The most beneficial physical activity for reducing abdominal obesity is aerobic exercise, and the effect of strength training is unclear.

Similarly, high-intensity exercise is not always better than moderate-intensity exercise. Even three months of walking can significantly reduce visceral fat.

Although there are many medications that can reduce body fat, lifestyle interventions may be as effective as or even more effective than medications.

The analysis found that meeting the current recommendation of 150 minutes of physical activity per week may be enough to reduce belly fat.

Should the dosage of antiplatelet drugs be adjusted for obese patients?

Studies have shown that obesity may promote platelet activation, and the inhibitory effect of platelets is weakened after the use of antiplatelet drugs. However, clinically, it has been found that obese patients with acute coronary syndrome have a better prognosis, which is inconsistent with the platelet test results. Since the sample size of the study is too small, it is impossible to draw a definitive conclusion about the clinical results. The statement does not make any recommendations on adjusting the dose of antiplatelet drugs for obese patients.

The harm of obesity is not entirely mediated by concurrent risk factors

Based on multiple prospective epidemiological studies, obesity is associated with a higher risk of coronary heart disease, which is mainly mediated by hypertension, dyslipidemia, diabetes and other comorbidities. Even after correcting for these risk factors, obesity still presents a significant residual risk of coronary heart disease.

The statement pointed out that excessive obesity can indirectly damage heart function through obesity-related comorbidities, and can also directly affect the myocardial and vascular systems.

In addition to the above-mentioned effects of excessive obesity on coronary adventitial vessels, obesity is also associated with coronary microvascular abnormalities.

However, currently, no studies have shown that weight loss through lifestyle changes can significantly reduce cardiovascular disease or mortality, although cardiovascular risk factors have improved.

Obesity is an independent risk factor for heart failure

Many studies have confirmed that obesity is a major cause of hypertension, cardiovascular disease and left ventricular hypertrophy

Risk factors: Many studies have confirmed that obesity is a major risk factor for heart failure.

Obesity has potential adverse effects on left ventricular systolic function, especially left ventricular diastolic function.

Other anthropometric parameters of excess adiposity, such as waist circumference, waist-to-hip ratio, and waist-to-height ratio, were also independently associated with HF risk.

Currently, there is little evidence that weight loss improves outcomes in patients with heart failure, but weight loss can reduce symptoms, improve quality of life and other comorbidities such as sleep apnea or diabetes. However, in patients with heart failure, there is an obesity paradox, where obese people have a relatively better prognosis.

Orlistat has limited efficacy and safety in treating obesity with heart failure. Newer glucose-lowering drugs, sodium-glucose cotransporter 2 inhibitors (SGLT2i) and glucagon-like peptide-1 receptor agonists (GLP-1A, such as liraglutide), have been shown to be effective in reducing weight and reducing hospitalizations for heart failure and cardiovascular death. Trials of these drugs are currently ongoing, and results will be available within the next 5 years.

Obese people also have an increased risk of sudden cardiac death and atrial fibrillation

The statement also noted that there is now convincing evidence that excess obesity is an important risk factor for cardiac arrhythmias, especially sudden cardiac death and atrial fibrillation.

For every 5-unit increase in body mass index, the risk of sudden cardiac death increases by 16%. Obesity is the most common non-ischemic cause of sudden cardiac death, and abdominal obesity plays an important role.

An estimated one in five cases of atrial fibrillation is associated with obesity. An elevated body mass index in midlife is strongly associated with the development of atrial fibrillation in later life.

There is also good evidence supporting the benefits of weight loss. The statement states that weight management should be part of the management of atrial fibrillation.

As the population ages, the prevalence of obesity in the elderly population is increasing, and there is a need to evaluate the potential mechanisms of obesity-related cardiac dysfunction and improve the management of patients with obesity and cardiovascular disease through future research.

The statement stressed that the sharp increase in the proportion of young patients with severe obesity requires more upstream intervention measures for primary prevention and better treatment of obesity as a chronic disease.

Source: China Circulation Magazine