Social conditions such as poverty, social isolation and inability to get or prepare preferred foods can cause unintentional weight loss, and this may be particularly common in older people.[42] Nutrient intake can also be affected by culture, family and belief systems.[27] Ill-fitting dentures and other dental or oral health problems can also affect adequacy of nutrition.[27]

Weight loss, in the context of medicine, health, or physical fitness, refers to a reduction of the total body mass, due to a mean loss of fluid, body fat or adipose tissue or lean mass, namely bone mineral deposits, muscle, tendon, and other connective tissue. Weight loss can either occur unintentionally due to malnourishment or an underlying disease or arise from a conscious effort to improve an actual or perceived overweight or obese state. "Unexplained" weight loss that is not caused by reduction in calorific intake or exercise is called cachexia and may be a symptom of a serious medical condition. Intentional weight loss is commonly referred to as slimming.
The least intrusive weight loss methods, and those most often recommended, are adjustments to eating patterns and increased physical activity, generally in the form of exercise. The World Health Organization recommended that people combine a reduction of processed foods high in saturated fats, sugar and salt[10] and caloric content of the diet with an increase in physical activity.[11]
Site enhancement oil, often called "santol" or "synthol" (no relation to the Synthol mouthwash brand), refers to oils injected into muscles to increase the size or change the shape. Some bodybuilders, particularly at the professional level, inject their muscles with such mixtures to mimic the appearance of developed muscle where it may otherwise be disproportionate or lacking.[55] This is known as "fluffing".[56][57] Synthol is 85% oil, 7.5% lidocaine, and 7.5% alcohol.[56] It is not restricted, and many brands are available on the Internet.[58] The use of injected oil to enhance muscle appearance is common among bodybuilders,[59][60] despite the fact that synthol can cause pulmonary embolisms, nerve damage, infections, sclerosing lipogranuloma,[61] stroke,[56] and the formation of oil-filled granulomas, cysts or ulcers in the muscle.[60][62][63] Rare cases might require surgical intervention to avoid further damage to the muscle and/or to prevent loss of life.[64]