The first priority in obesity treatment is to decrease calorie intake, usually by 500 to
1000 cal/day to achieve a weekly weight loss of 1 to 2 pounds (Seagle and Strain, 2009).
This recommendation is based on the assumption that 1 pound of fat mass is approximately
equivalent to 3500 calories and that this rate of weight loss remains constant
over a period of time. However, metabolic adaptations occur during weight loss (e.g.,
fewer calories expended during daily activities because body weight is lower) that require
a further decrease in calorie intake to achieve a negative calorie balance and continued
weight loss (Finkler, Heymsfi eld, and St-Onge, 2012). This is one factor that contributes
to the decreasing rate of weight loss that occurs as the duration of a diet increases
(Finkler et al., 2012).