The comparative and cumulative effects of a dietary restriction and exercise on weight loss

Abstract

Objective: To assess the independence of changes made in diet and physical activity for weight loss; and, to examine the comparative and cumulative effects of these behavioral changes on weight loss outcomes. Design: The observational study is based on longitudinal data collected from 674 women and 288 men enrolled in a 2-year weight loss program introduced into a managed care setting. Measurements: The outcome variable was body mass index (BMI) change from baseline to 2-year follow-up. Primary independent variables were changes in physical activity and dietary fat intake, assessed as continuous measures using the Paffenbarger Physical Activity Questionnaire and Block Fat Screener Questionnaire, respectively. Two-way ANCOVA was used to assess the relative effect on BMI of behavioral changes. Results: Study results showed no preference for diet or physical activity change as a weight loss strategy. For both genders, the relationship between the two behaviors was synergistic rather than compensatory. Examination of the comparative benefits of behavioral changes indicated that, for women and men, restricting fat intake was more effective than increasing exercise for weight loss. While fat restrictions alone contributed to weight loss in both genders, exercise alone provided weight loss benefits to men, only. The cumulative effect of weight loss behaviors varied by gender. In women, an interaction was observed. The response of weight to fat restriction was greater among those who increased their exercise moderately or substantially. In men, there was no interaction; exercise increases helped to offset weight gain or provided small weight loss benefits at all levels of dietary fat change. Conclusion: Dietary changes appeared to be more effective than increased physical activity for weight loss. For women, the cumulative effect of concomitant changes in diet and exercise on weight loss was more than additive.

Intervenção PRAdA: Efeitos no Peso Induzidos por Proposta de Alteração de Comportamento Alimentar em Hipertensos Medicados Nativos Portugueses e Imigrantes de Origem Africana

“…Este resultado é consistente com outras investigações, admitindo-se que estas diferenças entre os sexos tenham uma base biológica e associada à resposta ao exercício físico. 41 Verificou-se ainda a associação de fatores de risco cardiovascular -HTA não controlada, IMC mais elevado no grupo dos NOP, hipercolesterolémia no grupo dos NOP -com maiores perdas de peso ao longo da intervenção. Estes dados são sugestivos de que um maior risco cardiovascular é um fator de motivação para adesão às recomendações traduzindo-se em maior perda de peso.…”

Unfattening our children: forks over feet

“…38,39 Studies in adults suggest that the restriction of caloric intake is more reliably predictive of weight loss than increases in physical activity. 40 That said, the case for prioritizing attention to calories in over calories out is even stronger than the available scientific literature suggests. It is a case well made by an application of sense, and some very simple energy math.…”

Variability in adherence to an unsupervised exercise prescription in obese women

“…This study concurs with previous work suggesting that exercise is an integral component to the success of lifestyle interventions aimed at weight loss, as exercise adherers lost significantly more weight than non-adherers (an average of 9.9 vs 4.1 kg, Table 1). [28][29][30] The theoretical weight loss associated with full adherence to the exercise component of the intervention would have been approximately 3 kg (1500 kcal  16 weeks ¼ 24 000 kcal, where 7700 kcal expended ¼ weight loss of 1 kg). As the adherers group lost in excess of this projection, it is likely that members of this group were concurrently adhering to the prescribed dietary restriction (À500 kcal day…”

“…This is also consistent with previous work where 36% of a group of overweight women taking part in a lifestyle intervention made positive changes to both exercise and dietary habits. 30 The evidence base was summarized in a review by Hill and Wyatt, 31 which made the suggestion that exercise adherence may act as a strong predictor of weight loss success because it acts as a marker for compliance with other healthy behaviours.…”