We argue that despite inconsistencies in the definition , patterns across studies clearly show that healthy obesity is a state of intermediate disease risk .
Expert commentary : Given the current state of population -level evidence , we conclude that obesity and metabolic dysfunction are inseparable and that healthy obesity is best viewed only as a state of relative health but not of absolute health .
INTRODUCTION Obesity is a top public health priority but interventions to reverse the condition have had limited success .
About one-in-three obese adults are free of metabolic risk factor clustering and are considered ' healthy ' , and much attention has focused on the implication s of this state for obesity management .
Reduction in Obesity and Related Comorbid Conditions after Diet-Induced Weight Loss or Exercise-Induced Weight Loss in Men
In 1997 , the World Health Organization published a l and mark document recognizing obesity as a worldwide disease that poses a serious threat to public health ( 1 ) . Persons who are overweight or obese have substantially increased risk for morbidity from numerous chronic disorders , such as diabetes ( 2 , 3 ) , hypertension ( 4 , 5 ) , and cardiovascular disease ( 6 , 7 ) . Obesity-related health risk is greater when excess fat is deposited in the abdomen region because this phenotype is a stronger predictor of cardiovascular disease and type 2 diabetes mellitus than general obesity is ( 8 - 11 ) . This may be partially explained by excess accumulation of visceral fat , an independent correlate of insulin resistance ( 9 - 11 ) and dyslipidemia ( 8 , 9 ) . These observations highlight the need to identify appropriate treatment strategies to prevent and reduce obesity and suggest that the effectiveness of these treatments would be enhanced if abdominal obesity , particularly visceral fat , was substantially reduced . Diet restriction remains the most common method of obesity reduction ( 12 ) . Despite the observation that low levels of physical activity are a major cause of obesity ( 13 ) , increased physical activity alone is not thought to be a useful strategy for obesity reduction . Some reports have suggested that physical activity in obese adults results in only modest weight loss ( approximately 1 to 2 kg ) independent of the effects of diet restriction ( 14 ) . However , these conclusions are drawn from studies in which individual energy intake and expenditure were not rigorously controlled or accurately measured ( 15 - 17 ) . Moreover , in most studies , the negative energy balance induced by exercise was modest enough that substantial weight loss was not expected ( 15 - 17 ) . Currently , no compelling evidence supports the observation that exercise alone is not a useful method for reducing total or abdominal obesity . It is well known that a single exercise session is associated with a significant improvement in insulin-stimulated glucose uptake ( 18 , 19 ) . It is also clear that weight loss is associated with an improvement in insulin action ( 20 - 24 ) . It is unclear , however , whether regular exercise improves glucose metabolism after the short-term effects of exercise and changes in body fat distribution are considered . Segal and colleagues ( 25 ) controlled for the confounding effect of the last exercise session and body composition changes and found that exercise had no independent effect on insulin sensitivity ( 25 ) . Given the established importance of insulin resistance as an antecedent to both cardiovascular disease and type 2 diabetes mellitus ( 26 ) , it is important to clarify whether exercise improves insulin action independent of fat loss . We performed a r and omized , controlled trial to determine the independent effect of diet-induced or exercise-induced weight loss on obesity and insulin resistance in moderately obese men . We also evaluated whether exercise without weight loss was associated with reductions in abdominal obesity and insulin resistance . Methods Participants Participants were recruited from Kingston , Ontario , Canada , a typical suburban region , through the general media . We selected men with a body mass index greater than 27 kg/m2 and a waist circumference greater than 100 cm whose weight had been stable ( 2 kg ) for 6 months before study entry . Participants were nonsmokers who consumed an average of fewer than two alcoholic beverages per day , had a sedentary lifestyle , and took no medications known to affect the principal outcome measures . All participants had a preparticipation medical examination that included screening for normal glucose tolerance and plasma lipid profile . A computer program was used to r and omly assign eligible men to one of the following four groups : control , diet-induced weight loss , exercise-induced weight loss , and exercise without weight loss ( Figure 1 ) . Of the 101 participants who were r and omly assigned to groups , 34 chose not to participate because they were dissatisfied with their assigned group , 5 were diabetic or dyslipidemic , and 3 were relocated because of job transfers . Those who chose not to participate and those who completed the trial were similar with regard to anthropometric variables . In addition , those who completed the trial were similar to those who did not in each group ( P > 0.10 ) . Baseline characteristics among groups were similar for all participants ( Table 1 ) . All participants gave fully informed written consent . The study was conducted in accordance with the ethical guidelines of Queen 's University . The participants did not receive monetary compensation . Figure 1 . Flow of participants through the study . Table 1 . Selected Anthropometric , Magnetic Resonance Imaging , and Metabolic Variables before Treatment and 3 Months after Treatment Diet and Exercise Regimen During the baseline period , daily energy requirements for all participants were determined by estimating resting energy expenditure and multiplying the obtained value by a factor of 1.5 ( 27 ) . All participants followed a weight maintenance diet ( 55 % to 60 % carbohydrate , 15 % to 20 % protein , and 20 % to 25 % fat ) for a 4- to 5-week baseline period . During this period , body weight was monitored to determine the accuracy of the prescribed energy requirement , which was adjusted accordingly to maintain body weight . Controls were asked to maintain body weight throughout the 12-week treatment period . Participants in the diet-induced weight loss group were asked to reduce the isocaloric diet by 700 kcal/d during the treatment period to achieve a weekly weight loss of approximately 0.6 kg . To lose the same amount of weight , participants in the exercise-induced weight loss group were asked to maintain the isocaloric diet for the duration of the treatment period and to perform exercise that expended 700 kcal/d . Participants assigned to exercise without weight loss were asked to maintain body weight . Therefore , they consumed enough calories to compensate for the energy expended during the daily exercise sessions ( approximately 700 kcal ) . At the end of the treatment period , isocaloric requirements were determined and prescribed for a 2-week weight stabilization period . All participants were free-living and consumed self-selected foods .  No vitamins or other nutritional supplements were prescribed . Each person participated in a series of weekly 1-hour seminars in which a dietitian taught proper food selection and preparation . Participants were told that the composition of the maintenance and energy-reduced diets should be approximately 55 % to 60 % carbohydrate , 15 % to 20 % protein , and 20 % to 25 % fat . Participants kept and analyzed daily , detailed food records for the duration of the study period ( approximately 20 weeks ) ; the study dietitian also review ed these records . For the 2-week period during which doubly labeled water measurements were acquired ( weeks 6 and 7 ) , the diet records were analyzed by using a computerized program ( Food Processor , Esha Research , Salem , Oregon ) . Participants in both exercise groups performed daily exercise ( brisk walking or light jogging ) on a motorized treadmill for the duration of the 12-week trial . The length of each exercise session was determined by the time required to expend 700 kcal . Participants were asked to exercise at an intensity not greater than 70 % of their peak oxygen uptake ( Vo 2 ) ( approximately 80 % of maximal heart rate ) . Energy expenditure was determined by using the heart rate and oxygen consumption data that were obtained from the pretreatment grade d exercise test and were adjusted according to the results of two subsequent tests performed at weeks 4 and 8 . During each session , heart rate was monitored every 5 minutes by using an automated heart rate monitor ( Polar Oy , Kempele , Finl and ) . All exercise sessions were by appointment and were supervised . Peak Vo 2 was determined by using a grade d treadmill test and st and ard open-circuit spirometry techniques ( SensorMedics , Yorba Linda , California ) . Energy Expenditure Total energy expenditure for 14 days was measured by using a two-point doubly labeled water method ( 28 ) . Deuterium enrichment was analyzed by using a 903 deuterium dual-inlet isotope ratio mass spectrometer ( VG Isogas , Cheshire , United Kingdom ) . Oxygen-18 was determined by using a SIRA 12 isotope ratio mass spectrometer ( VG Isogas ) . Total energy expenditure was calculated by using the DeWeir formula ( 29 ) . After an overnight stay in the hospital , resting metabolic rate was measured at 7:00 a.m. by using indirect calorimetry with a modified mask system ( Teem 100 , Aerosport , Inc. , Ann Arbor , Michigan ) . Values were obtained for 30 minutes , and the last 25 minutes were used to determine resting metabolic rate . Resting systolic and diastolic blood pressure were measured when the participant was supine . Magnetic Resonance Imaging and Anthropometric Measurements Whole-body data from magnetic resonance imaging ( approximately 45 equidistant images ) were obtained with a General Electric 1.5-Tesla magnet ( Milwaukee , Wisconsin ) by using an established protocol described in detail elsewhere ( 30 ) . Once acquired , the data were transferred to a st and -alone work station ( Silicon Graphics , Mountain View , California ) for analysis with specially design ed computer software ( Tomovision , Inc. , Montreal , Canada ) , the procedures for which are described elsewhere ( 31 ) . For adipose tissue ( fat ) and skeletal muscle , volume units ( L ) were converted to mass units ( kg ) by multiplying the volumes by the assumed constant density for fat ( 0.92 kg/L ) and fat-free skeletal muscle ( 1.04 kg/L ) ( 32 ) . All anthropometric circumference measurements were obtained by using st and ard procedures described elsewhere ( 30 ) . Insulin Sensitivity and Glucose Tolerance Participants consumed a weight-maintenance diet consisting of at least 200 g of carbohydrate for a minimum of 4 days and were asked to avoid strenuous physical activity for 3 days before insulin
We argue that despite inconsistencies in the definition , patterns across studies clearly show that healthy obesity is a state of intermediate disease risk .
Expert commentary : Given the current state of population -level evidence , we conclude that obesity and metabolic dysfunction are inseparable and that healthy obesity is best viewed only as a state of relative health but not of absolute health .
INTRODUCTION Obesity is a top public health priority but interventions to reverse the condition have had limited success .
About one-in-three obese adults are free of metabolic risk factor clustering and are considered ' healthy ' , and much attention has focused on the implication s of this state for obesity management .