行为和生活方式的选择也基本因素在一个人的体重,和发展的关键因素是肥胖的一种不健康的饮食和很少或根本没有身体活动是主要的风险因素变得超重或肥胖,除了许多其他慢性疾病,如心血管疾病,糖尿病,高血压,和某些形式的癌症。身体活动是决定能量利用的关键因素，而能量利用对减肥和控制体重都至关重要。美国卫生部(Department of Health)目前的建议规定，成年人每周至少要花150分钟进行至少中等强度的有氧运动，5岁以上儿童每天至少要花60分钟进行体育活动。然而，最近的研究表明，即使是那些按照建议水平锻炼的人，如果他们在其他方面长时间久坐不动，他们的健康状况也会更差。将体育活动纳入日常生活是很重要的，因为研究表明，无论是在学校还是在社区环境中，体育活动至少与通过监督下的锻炼计划减肥一样有效，如果不是更有效的话。进一步的研究也表明，规律的有氧运动是降低心血管疾病风险的最有效的运动形式，也可以作为一种有效的治疗周围血管疾病。
Behaviour and lifestyle choices are also fundamental factors in a person’s weight, and are key factors in the development of obesity A combination of an unhealthy diet and little or no physical activity are major risk factors for becoming overweight or obese, in addition to a number of other chronic health conditions, such as cardiovascular disease, diabetes, hypertension, and some forms of cancer . Physical activity is a key factor in determining energy utilisation, which is key in both weight loss and control,. Current recommendations from the Department of Health stipulate that adults spend at least 150 minutes a week performing aerobic activity of at least moderate intensity, and children over the age of 5 should spend at least 60 minutes doing physical activity each day . However, recent research has demonstrated that even those who exercise at the recommended levels are still at higher risk of poor health outcomes if they are still otherwise sedentary for a large amount of time . It is important that physical activity is incorporated into regular daily life, as research has shown that this is at least as effective, if not more effective, than weight loss through a supervised exercise programme, either in schools or in a community setting . Further research has also shown that regular aerobic exercise is the most effective form of exercise when reducing the risk of cardiovascular disease and can also be used as an effective treatment for peripheral vascular disease .