Weight management programs abound, and they employ countless strategies and approaches. But all these programs should include three principal components: (1) an exercise plan that incorporates cardiovascular and resistance training to increase caloric expenditure and maintain muscle mass; (2) a lifestyle/ dietary approach that emphasizes balanced nutrition and decreased caloric intake; and (3) a behavior modification strategy to support implementation of the exercise and lifestyle components. With fitness industry professionals, perhaps the one topic--or obsession--that will surely generate debate in the exercise component of the plan is, What is the best exercise fat-burning zone? This article will attempt to bring clarity where there is cloudiness, research where there is perception, and guidance where there is dissent on this contestable issue and related matters.
Energy Balance Basics
A kilocalorie (hereafter referred to as a calorie) is a unit of energy, and since energy is neither created nor destroyed (according to the first law of thermodynamics), the calories you eat will either be stored somewhere in your body or expended for fuel in metabolism for your daily activities, occupational tasks and exercise. This basic theory specifies that consuming more energy than you expend will lead to a positive energy balance--and weight gain. Conversely, expending more energy than you consume will lead to a negative energy balance--and weight loss. However, due to individual differences in the body's neurological, hormonal and metabolic regulatory systems, this concept of caloric balance does not work to precisely the same degree in all persons.
When a person has a negative energy balance, weight loss may come from three body sources: water, adipose tissue (fat) and muscle tissue. Under most circumstances, body water will remain relatively normal as long as regular hydration is maintained. The goal of a weight loss plan is to lose fat while preserving muscle mass.
Is Low-Intensity Exercise Better for Fat Burning?
We've all heard the claim that the best type of cardiovascular training for burning fat is lower-intensity exercise, which keeps the exerciser in the so-called "fat-burning zone." Thompson and colleagues (1998) have confirmed that at lower intensities (50% V[O.sub.2]max), a greater percentage of energy comes from fat than at higher intensities (70% V[O.sub.2]max). However, as long as workouts are the same length, the total energy...
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