Exercise for weight loss: what are the facts?

Appetite Control Is Improved by Acute Increases in Energy Turnover at Different Levels of Energy Balance

BACKGROUND

Weight control is hypothesized to be improved when physical activity and energy intake are both high [high energy turnover (ET)].

OBJECTIVE

The impact of three levels of ET on short-term appetite control is therefore investigated at fixed levels of energy balance.

DESIGN

In a randomized crossover trial, 16 healthy adults (25.1 ± 3.9 y of age; body mass index, 24.0 ± 3.2 kg/m2) spent three daylong protocols for four times in a metabolic chamber. Four conditions of energy balance (ad libitum energy intake, zero energy balance, -25% caloric restriction, and +25% overfeeding) were each performed at three levels of ET (PAL 1.3 low, 1.6 medium, and 1.8 high ET; by walking on a treadmill). Levels of appetite hormones ghrelin, GLP-1, and insulin (total area under the curve) were measured during 14 hours. Subjective appetite ratings were assessed by visual analog scales.

RESULTS

Compared with high ET, low ET led to decreased GLP-1 (at all energy balance conditions: P < 0.001) and increased ghrelin concentrations (caloric restriction and overfeeding: P < 0.001), which was consistent with higher feelings of hunger (zero energy balance: P < 0.001) and desire to eat (all energy balance conditions: P < 0.05) and a positive energy balance during ad libitum intake (+17.5%; P < 0.001).

CONCLUSION

Appetite is regulated more effectively at a high level of ET, whereas overeating and consequently weight gain are likely to occur at low levels of ET. In contrast to the prevailing concept of body weight control, the positive impact of physical activity is independent from burning up more calories and is explained by improved appetite sensations.

Not very NICE: deviance, stigma and nutritional guidelines related to healthy weight and obesity

This paper critically examines the current National Institute for Health and Clinical Excellence and National Health Service guidelines on weight management and the avoidance of obesity (NG7). We demonstrate that the guidance is unlikely to produce the desired effect of enabling people to reduce or control their weight through the twin strategies of dieting (primarily using the calories-in, calories-out approach) and increasing their levels of exercise. The paper provides a critical examination of these guidelines and concludes that they are unlikely to encourage maintenance of 'healthy' weights or prevent obesity, are not based upon particularly strong evidence and are misguided in maintaining a persistent focus upon weight rather than other indicators of health. Moreover, we suggest their promotion may produce a number of unintended consequences, including perpetuating body-related stigmatisation and anxieties. Copyright © 2016 John Wiley & Sons, Ltd.

Intermittent versus continuous exercise: effects of perceptually lower exercise in obese women

INTRODUCTION

Exercise has beneficial effects on obesity and diabetes treatments. However, obese subjects do not closely adhere to training programs probably because of the monotony of the continuous exercise that is frequently proposed. To increase adherence to training programs, intermittent exercise, which is less monotonous, may be more appropriate.

PURPOSE

The purposes of this study were to determine the perceptually less hard exercise (continuous vs intermittent exercise) and to analyze the impact of a training program on the basis of this exercise in obese women with and without type 2 diabetes.

METHODS

Twenty type 2 diabetic obese women and 20 obese women without diabetes were recruited. In each group, 10 patients integrated a training program (i.e., training groups), whereas the remaining patients were untrained (i.e., control groups). The training groups performed a continuous exercise and an intermittent exercise to determine the perceptually less hard exercise thanks to lower ratings of perceived exertion (RPE). Then, a training program that included 32 min (3 d x wk(-1) x 10 wk(-1)) of the perceptually less hard exercise was proposed to training groups.

RESULTS

RPE were significantly lower during the intermittent exercise compared to the continuous exercise in the obese women with or without diabetes (RPE = 12.3 +/- 2.3 vs 13.7 +/- 2.3 and RPE = 11.9 +/- 1.1 vs 13.2 +/- 1.6, respectively). After the training program, significant beneficial effects on the glycosylated hemoglobin (6.8 +/- 1.4% vs 6.5 +/- 1.2%), body mass (97.1 +/- 16.9 vs 95.2 +/- 16.2 kg), body mass index (37.6 +/- 6.1 vs 36.8 +/- 6.0 kg x m(-2)), and on the HR and the walked distance limit were noticed in the training groups.

CONCLUSION

The obese women with or without diabetes perceived the intermittent exercise as being less hard than the continuous exercise, and a training program based on intermittent exercises produced beneficial effects on obesity and type 2 diabetes.

[Effects of intermittent walk program on the body mass and composition in obese women]

The obese patients adhere weakly to rehabilitation programs; therefore the expected gains are often disappointing. This is possibly linked to the monotony of constant velocity exercises frequently proposed. Consequently, other less monotonous exercises such as the intermittent walk may be more appropriated.

OBJECTIVES

The main objectives of this study were to determine if the obese women prefer a constant velocity walk or an intermittent walk, and to analyze the effects of a rehabilitation program based on the intermittent walk.

MATERIALS AND METHODS

Twenty obese women were recruited. To determine the preferred walk modality, 10 obese women performed a constant velocity walk and an intermittent walk (with a similar duration and velocity) on a treadmill. The preferred walk modality was determined by lower ratings of perceived exertion. Then, these same 10 women participated in a rehabilitation program of 10 weeks (three days per week) consisting of intermittent walks. The 10 other women did not participate in a training program.

RESULTS

The ratings of perceived exertion were not significantly different between the two walk modalities. However, the women who participated in a training program increased their maximal distance during a 6 min walking test and they have stabilized theirs anthropometric data. Meanwhile, the untrained women have increased their body mass, body mass index and percentage of body fat.

CONCLUSION

The obese patients preferred similarly the constant velocity walk and the intermittent walk, and a rehabilitation program based on an intermittent walk is effective in avoiding the obesity aggravation.

Safe and effective management of the obese patient

The prevalence of overweight and obesity has increased dramatically in the recent decades, and obesity is now a major public health problem. Obesity negatively influences an individual's health by increasing mortality and raising the risk for multiple medical conditions such as type 2 diabetes mellitus, hypertension, dyslipidemia, and coronary heart disease. In addition, the obese individual is often the brunt of social discrimination. Weight loss has been shown to reduce the risk for many of these comorbid conditions. A multifaceted approach to the obese patient should include identifying potential causes for weight gain, outlining medical conditions that would benefit by weight loss, and tailoring a weight loss program that is safe and effective for the individual. Components of a successful weight loss program include dietary intervention, recommendations for physical activity, behavior modification, and, in a select group of patients, pharmacologic or surgical intervention.

Perceived benefits and barriers to physical activity in a nationally representative sample in the European Union

OBJECTIVE

To examine the attitudes of consumers, in particular their perceived benefits and barriers to physical activity from all EU member states, and having a measure of prevailing levels of activity, inactivity and self-reported body weight and body shape.

DESIGN

Cross-sectional survey using an interview-assisted face-to-face questionnaire.

SETTING

The survey was conducted between March and April 1997 in the 15 member states of the EU.

SUBJECTS

Overall, 15,239 EU subjects, classified according to sex, age (six levels) and highest level of education attained (primary, secondary or tertiary), completed the survey. Sample selection of subjects in each EU member state was quota-controlled to ensure they were nationally representative.

RESULTS

The most important motivation for people to participate in physical activity is to maintain good health (42%), to release tension (30%) and to get fit (30%). The importance of the health argument is highest in older persons and in subjects with a primary education level. Only 13% of the EU population (16% of women, 10% of men) perceived losing weight as a benefit of physical exercise. The most important barriers to increase physical activity are work or study commitments (28%) and the subjects' belief that they are not 'the sporty type' (25%). There is considerable between-country variation in the answering pattern within the EU.

Exercise prescription for weight management

The debate surrounding the level of intensity of exercise that is best for health improvement has potentially clouded the issue of optimal exercise prescription for weight management. Low-intensity activity is potentially superior to moderate to high intensity for improving metabolic risk factors, and accumulated small bouts of physical activity are as effective to this end as single longer bouts, as long as the overall volume of energy expenditure is equivalent. What should not be forgotten however, is that for weight-loss it is the total volume of energy expended that will dictate the size of the energy deficit imposed, not the composition of the exercise per se. Exercise prescription for weight management is a conundrum. Whilst it is the total volume of energy expended that will dictate the magnitude of weight lost, not the composition of the exercise per se, it is the nature of the exercise prescription that will dictate the long-term success of an exercise programme. It is how well the exercise prescription is individualized that influences tolerance of and interest in the programme and, thus, the adherence to it in the long term.

A worksite program for overweight middle-aged men achieves lesser weight loss with exercise than with dietary change

OBJECTIVE

To compare changes in total and regional body composition using dual energy X-ray absorptiometry (DEXA) after subjects lost weight through change in diet or exercise.

DESIGN

A 12-month, randomized, controlled study of two weight-loss interventions-low-fat diet ad libitum or moderate, unsupervised exercise-in free-living, middle-aged men. Compliance was determined at monthly measurement sessions through food records and activity logs; DEXA scans were performed every 3 months.

SUBJECTS/SETTING

Fifty-eight overweight men (mean body mass index = 29.0 +/- 2.6; mean age = 43.4 +/- 5.7 years) recruited from a national corporation were assigned randomly to diet, exercise, or control groups.

INTERVENTIONS

One group reduced dietary fat to 26.4% of energy intake but kept activity unchanged; another group self-selected aerobic exercise (three sessions per week at 65% to 75% maximum heart rate) but kept diet unchanged. A control group maintained weight.

MAIN OUTCOME MEASURES

At 12 months, measurements of weight, total and regional fat mass and lean mass, energy intake, and percentage dietary fat; physical activity indexes.

STATISTICAL ANALYSES

Results were analyzed using paired t tests and analysis of variance.

RESULTS

Mean weight loss was 6.4 +/- 3.3 kg in dieters and 2.6 +/- 3.0 kg in exercisers; control subjects maintained weight. DEXA scans revealed that 40% of dieters' weight loss was lean tissue; more than 80% of weight lost by exercisers was fat. Exercisers maintained limb lean tissue and lost fat mass.

CONCLUSIONS

Greater total weight and lean tissue loss occurred when subjects lost weight through a low-fat diet consumed ad libitum than when subjects participated in unsupervised aerobic exercise. Use of DEXA enabled identification of progressive total and regional changes in fat and lean tissue.