Obesity is thought to be a heterogeneous disorder with several possible etiologies; therefore, by examining subtypes of obesity we attempt to understand obesity's heterogeneous nature. The purpose of this review was to investigate the roles of metabolic, body composition, and cardiovascular disease risk in subtypes of obesity. We briefly consider two subtypes of obesity that have been identified in the literature. One subset of individuals, termed the metabolically healthy, but obese (MHO), despite having large amounts of fat mass compared with at risk obese individuals shows a normal metabolic profile, but remarkably normal to high levels of insulin sensitivity. Preliminary evidence suggests that this could be due at least in part to lower visceral fat levels and earlier onset of obesity. A second subset, termed the metabolically obese, but normal weight (MONW), present with normal body mass index, but have significant risk factors for diabetes, metabolic syndrome, and cardiovascular disease, which could be due to higher fat mass and plasma triglycerides as well as higher visceral fat and liver content. We also briefly consider the potential role of adipose and gastrointestinal hormonal profiles in MHO and MONW individuals, which could lead to a better understanding of potential factors that may regulate their body composition. This information will eventually be invaluable in helping us understand factors that predispose to or protect obese individuals from metabolic and cardiovascular disease. Collectively, a greater understanding of the MHO and MONW individual has important implications for therapeutic decision making, the characterization of subjects in research protocols, and medical education.

No abstract

Natural menopause is associated with reduced energy expenditure during rest and physical activity, an accelerated loss of fat-free mass, and increased central adiposity and fasting insulin levels. These changes may indicate a worsening cardiovascular and metabolic risk profile.

Endurance training does not enhance total energy expenditure in healthy elderly persons. Am. J. Physiol. 263 (Endocrinol. Metub. 26):E950-E957, 1992.-Physical exercise is prescribed to older individuals to increase cardiovascular fitness and improve body composition. However, there is limited information on the effect of exercise on total energy expenditure (TEE) and its components. We therefore determined the effects of short-term endurance training in 11 elderly volunteers (56-78 years) on changes in 1) TEE, from doubly labeled water; 2) resting metabolic rate (RMR), from respiratory gas analysis, 3) the energy expenditure of physical activity (EEPA), aside from that associated with the training program, and 4) body composition from a combination of body density with total body water. Endurance training increased maximum oxygen consumption (VO, max) by 9% (2.00 t 0.67 to 2.17 t 0.64 l/min; P < 0.05) and RMR by 11% (1,596 t 214 to 1,763 t 170 kcal/day; P < 0.01). There was no significant change in TEE (2,408 t 478 to 2,479 & 497 kcal/day) before and during the last 10 days of endurance training because of a 62% reduction in EEPA (571 t 386 to 340 t 452 kcal/day; P < 0.01). There was no change in body mass, but fat mass decreased (21.6 t 6.6 to 20.7 t 6.6 kg; P < 0.05). The increase in fat-free mass (49.5 t 9.0 to 50.4 t 9.1 kg; P < 0.05) was explained by an increase in body water (35.9 t 6.5 to 36.8 & 6.3 kg; P < 0.05). We conclude that in healthy elderly persons, endurance training enhances cardiovascular fitness, but does not increase TEE because of a compensatory decline in physical activity during the remainder of the day. aging; physical activity; body composition; physical fitness; exercise THE AGING PROCESS is associated with several deleterious changes in body composition and whole body energy metabolism. These changes include an increase in adiposity (6), a loss of muscle mass (6), a decline in physical activity (5, 19, and a fall in resting metabolic rate (14, 18, 19). It is unclear whether these changes are due to the aging process per se or are more reflective of changes in lifestyle. Exercise is frequently prescribed to elderly persons to improve body composition, enhance energy expenditure, and increase functional independence.Endurance exercise is generally thought to increase total energy expenditure because of the direct energy cost of the exercise itself, the energy expenditure during the immediate postexercise period (l), and possibly an elevation in resting metabolic rate (E), although this effect is not seen in all studies (12). It is unknown whether exercise participation affects the daily energy cost of other physical activities during the remainder of the day. The energy expenditure associated with daily physical activities includes the energy cost required for the activities of daily living, exercise, spontaneous physical activity, and fidgeting. This component of daily energy expenditure has been shown to contribute a total of 138 to 685 kcal/day in young males when measured in a room...