Obesity is becoming more prevalent in industrialized countries and medical interventions have not been met with any sustained success to offset this trend. In Industrialized societies, the prevalence of obesity is higher in specific racial and ethnic groups. The capacity of some individuals to – activate – their nonexercise activity thermogenesis (NEAT) to buffer weight gain was a remarkable finding, and it highlights the importance of nonpurposeful physical activity as an important predictor of the heterogenecity of fat gain in humans.
Growing evidence points toward the menopause transition as a critical period in a womans life that may trigger the accumulation of total and central body fat.
Goodpaster BH, Kelley DE, Wing RR, et al (Univ of Pittsburgh, Pa)
Effects of Weight Loss on Regional Fat Distribution and Insulin Sensitivity in Obesity.
Diabetes 48: 839-847, 1999
Background: Weight loss reduces regional depots of adipose tissue and improves insulin sensitivity, which are correlated before weight loss.
Methods : Thirty-two obese sedentary women and men completed a 4-month weight loss program, which included repeat determination of body composition, assessed by dual-energy x-ray absorptiometry and CT, and insulin sensitivity, assessed by euglycemic insulin infusion. Fifteen lean men and women composed a control group.
Findings: Serum leptin, triglycerides, cholesterol, and insulin were reduced after weight loss.
Conclusion: These findings highlight the potential importance of visceral adiposity in relation to insulin resistance. Above a certain threshold of weight loss, insulin sensitivity improvement may not be linearly associated with weight loss magnitude.
Editorial comment: The results of this interesting study highlight the importance of reducing visceral body fat to attain improvements in insulin sensitivity in obese individuals undergoing weight loss. These results are particularly striking given that the quantity of intra-abdominal fat is only approximately 25% of the cross-sectional abdominal tissue, but it appears to be preferentially mobilized (compared with other compartments of regional body fat) in response to weight loss.
Baxter John, Prof. of Gen.Surg.(Univ.of Wales, Swansea)
Obesity surgery – another unmet need. It is effective but prejudice is preventing its use.
Inspite of diet, exercise and drugs, obese persons remain obese. Temporary loss of weight is again replenished with passage of time.
One of the most effective ways of losing weight permanently is by surgery. This is not liposuction but a laparoscopic band around the stomach. Not only is weight lost but there is improvement in type II diabetes, lowering of high blood pressure in hypertension and improvement in lipid profile in the blood. That is, almost all the abnormalities caused by obesity are corrected. Unfortunately, this procedure has not become popular and it is worthwhile for surgeons to take this up.
Dvorak RV, Tchernof A, Starling RD, et al (Univ of Vermont, Burlington; Yale Univ, New Haven, Conn)
Respiratory Fitness, Free Living Physical Activity, and Cardiovascular Disease Risk in Older Individuals: A Doubly Labeled Water Study
J Clin Endocrinol Metab 85: 957-963, 2000
This study included 117 elderly persons: 53 men (mean age 68 years) and 63 women (mean age 67 years).
The authors conclude that in older adults a high level of cardiorespiratory fitness is more strongly related to a favorable cardiovascular disease (CVD) risk factor profile than is a high level of physical activity.
The results of this analysis suggests that exercise programs for the elderly should emphasize aerobic activity for increased cardiorespiratory fitness.
Wareham NJ, Wong M-Y, Day NE (Univ of Cambridge, England; Hong Kong Univ of Science and Technology, People’s Republic of China; Medical Research Council, Cambridge, England)
Glucose Intolerance and Physical Inactivity: The Relative Importance of Low Habitual Energy Expenditure and Cardiorespiratory Fitness
Am J Epidemiol 152: 132-139, 2000
Physical inactivity is a key risk factor for diabetes. The above study included 775 volunteers without known diabetes when first assessed (age group 45-70 years).
The association of energy expenditure and cardiorespiratory fitness with glucose intolerance was assessed.
The 2-hour glucose level was negatively correlated with physical activity level and with maximal aerobic fitness. However the glucose level was positively correlated with age and obesity.
Energy expenditure had more effect on glucose intolerance than did cardiorespiratory fitness. Hence diabetes prevention programs should focus on increasing the overall energy expenditure.
Purnell JQ, Kahn SE, Albers JJ, et al (Univ of Washington, Seattle)
Effect of Weight Loss With Reduction of Intra-abdominal Fat on Lipid Metabolism in Older Men
J Clin Endocrinol Metab 85: 977-982, 2000
This study included 21 healthy men, averaging 65 years age, with obesity and a mean body mass index of 31 kg/m2. All subjects followed a 3 month weight loss protocol during which an average 10% weight loss was achieved.
It was found that weight loss (in older obese men) was associated with significant improvements in visceral adiposity, insulin sensitivity, hepatic lipase activity and dyslipidemia associated with visceral adiposity.
Alterations in intra-abdominal fat seem to have an important impact on hepatic lipase activity and thus on lipid parameters.
Ross R, Dagnone D, Jones PJH, et al (Queen’s Univ, Kingston, Ont, Canada; McGill Univ, Montreal)
Reduction in Obesity and Related Comorbid Conditions After Diet-Induced Weight Loss or Exercise-Induced Weight Loss in Men: A Randomized, Controlled Trial
Ann Intern Med 133: 92-103, 2000
This was a randomized controlled trial of 52 obese men, divided into 4 groups.
(1) Loss of weight through dietary restriction.
(2) Loss of weight through exercise only, (without caloric restriction).
(3) Exercised without weight loss.
(4) Control group.
It was found that weight loss through exercise only (without dietary restriction) is associated with significant reduction in abdominal obesity and insulin resistance.
The 3rd group (exercise without weight loss) also showed reduced abdominal fat.
Exercise-induced weight loss leads to a greater reduction in total fat and a greater improvement in cardiovascular function, than does equivalent amount of diet-induced weight loss.
Gallagher D, Ruts E, Visser M, et al (Columbia Univ, New York; Inst for Research in Extramural Medicine, Amsterdam; Univ of New Mexico, Albuquerque)
Weight Stability Masks Sarcopenia in Elderly Men and Women
Ann J Phys Med Rehabil 279: E366-E375, 2000
The data collected, indicated that sarcopenia occurs progressively, especially in elderly men, and even in healthy adults who may not demonstrate a reduction in body weight.
Murgatroyd PR, Goldberg GR, Leahy FE, et al (MRC Dunn Clinical Nutrition Centre, Cambridge, England)
Effect of Inactivity and Diet Composition on Human Energy Balance
Int J Obes 23: 1269-1275, 1999
This study assessed the effects of physical activity and dietary macronutrient composition on energy and fat balance.
Over a 2-day period normal subjects do not alter their energy intake in response to a high versus a low fat diet nor to physical inactivity.
Physical activity appears necessary to avoid a positive energy balance, regardless of dietary composition.
Molarius A, for the WHO MONICA Project (Natl Public Health Inst, Helsinki; et al)
Educational level, Relative Body weight, and Changes in their Association Over 10 years: An International Perspective From the WHO MONICA Project.
Am J Public Health 90: 1260-1268, 2000
Data on age-adjusted mean body mass index (BMI) and years of schooling were compiled on 26 populations participating in the initial and final surveys of the MONICA (monitoring trends and determinants in cardiovascular disease) project.
The initial survey included 42000 men and women aged 35 to 64 yrs; the final survey included nearly 35,000 participants.
It was found that women having a greater level of education had lower relative body weights; those who had less education had a higher BMI in almost all cases. In men, the differences were present in about ½ the cases studied.