For something that can’t be bottled, trademarked, or price-hiked for an exorbitant profit, walking has received remarkable publicity in recent years. From throngs of Fitbit wearers counting their steps to a growing awareness about walking’s benefits for mood and cognition, the benefits of this simple activity are gaining traction. In fact, according to Center for Disease Control estimates, over 150 million American adults partake in at least one 10-minute bout of walking each week, making it the most common form of aerobic activity in the nation.
But when it comes to weight loss, the effects of walking are less clear-cut. On one hand, any form of exercise should—all else being equal—contribute to the calorie deficit needed to shed pounds. Yet the actual energy expenditure from moderate intensity activities like walking tends to be low, and controlled trials suggest that aerobic exercise on its own isn’t an effective weight loss strategy for overweight and obese individuals. So, while reductions in blood pressure and other cardiometabolic risk factors might make it a worthy activity for health in general, it shouldn’t be assumed that walking alone translates to a leaner physique.
Despite disappointing results as a solo intervention, walking might still boost fat loss within the context of calorie restriction. A common problem among dieters is a decline in resting energy expenditure (REE), as shown in Figure 1. This decline can be attributed to two factors: a weight loss-induced decrease in lean tissue (which guzzles energy simply by existing), and a possible drop in the metabolic rate of major organs (which significantly impacts how much energy the body burns at rest). This results in reduced daily energy requirements, leading to slower—or stalled—weight loss that requires ever-steeper calorie reductions to maintain. High-intensity exercise has been shown to help preserve lean mass and offset decreases in REE, but isn’t always feasible for people with overweight or obesity due to orthopedic problems, increased injury risk, lower cardiovascular fitness, and poor compliance. That raises the question: could lower-intensity activity like walking accomplish the same thing in a more sustainable way?
Given the growing burden of obesity across the globe, understanding the nuances of fat loss is a goal that could benefit millions. And despite what seems like endless weight loss-related headlines bursting from media outlets every day, our understanding of how exercise interacts with diet in real-world settings still has room for improvement. The goal of the study at hand was to address this knowledge gap by testing whether adding a walking program to an energy-reduced diet could maintain REE, enhance fat loss, and improve body composition compared to dieting alone.
The impact of walking on weight loss has been underwhelming in exercise intervention studies, but little is known about its effect on REE and body composition in people consuming energy-reduced diets. If effective, walking may be a more feasible alternative to higher-intensity aerobic activity for dieters with obesity. The goal of this study was to determine whether combining a walking program with calorie restriction would prevent reductions in REE, enhance fat loss, and preserve lean tissue among people trying to lose weight.