Increased calcium does not impact weight loss
Nutrition Research Newsletter, Dec, 2005
Obesity affects one-third of adults in the United States and is approaching $100 billion annually in healthcare costs. Efforts aimed at decreasing obesity have focused primarily on treatment approaches designed to manage energy balance through calorie restriction (CR) and exercise. The role of micronutrients in energy balance remains understudied.
Epidemiological and cross-sectional investigations began to identify calcium intake as a dietary constituent that was inversely related to body weight and body fat levels. One hypothesis generated postulates that low calcium intake leads to increased intracellular calcium levels due to a change in circulating calcium-regulating hormones, particularly 1,25-dihyroxyvitamin D and parathyroid hormone. High intracellular calcium levels, in turn, act to reduce lipolysis and increase lipogenesis in adipocytes. Increasing dietary calcium is thought to inhibit these effects and facilitate fat loss.
The role of parathyroid hormone and 1,25 dihydroxy vitamin D in the regulation of body weight and the magnitude of the calcium-body weight relationship remain unclear. In light of this controversy, it is unclear how prominent a position calcium should play in the treatment of obesity. Additionally, at present, there are no data on the long-term weight loss efficacy of following a high-calcium diet beyond 6 months.
A study was performed to determine whether the weight loss and body composition of subjects on a calorie restricted diet with and without high levels of dairy calcium intake would differ at 3-, 6-, and 12-month time points. Fifty-four overweight and obese adults were recruited to participate. Eligibility criteria included age between 18 years and 60 years, BMI between 25 kg/[m.sup.2] and 34.9 kg/[m.sup.2], current calcium consumption = 500 mg/day, current dairy product consumption < 1 serving per day, no medical problems that would contraindicate CR and nonsmokers.
Interested individuals participated in four screening sessions. By phone, they were initially screened for baseline calcium intake, availability, medical history, BMI, and usual dairy calcium intake. Subjects were excluded if they consumed more than one serving of dairy products per day. If eligible, they were invited to attend an orientation session where the study was described in more detail. All subjects participated in a screening history and physical. Screening visit 3 involved an interview where subjects were asked to report on their motivations, expectations, barriers, eating behaviors, food aversion, and allergies. They also completed the Beck Depression Inventory and the Taylor Manifest Anxiety Scale. At screening visit 4, food records were visually assessed for total calcium consumption by scanning for servings of dairy and high-calcium foods. Those eligible were randomized to one of two conditions: CR + dairy (CR + D; n = 25) or CR (n = 29).
Subjects participated in a 12-month behavioral weight loss program. The weight loss treatment program focused on the modification of eating and exercise habits through the use of behavioral strategies and self-management skills. Subjects were given prescribed menus, grocery lists, and recipes specific to their dietary condition. Calorie goals were formulated to represent a 500 kcal/day restriction from baseline levels. The treatment programs differed only in the diets prescribed. The CR+D group was provided menus that included three to four servings of dairy products per day (milk, yogurt, and cheese) with a dairy calcium intake goal of 1200 mg/day to 1400 mg/day. The diet was structured to provide 10% to 15% of calories from protein, 55% to 65% carbohydrate, 30% fat, and 25 grams of fiber per day. Participants in the CR condition were provided menus, grocery lists, and recipes that included approximately one serving of dairy per day with a total calcium intake goal of 400 mg/day to 500 mg/day.
There were no significant differences between groups at baseline. At 12 months, weight and body fat loss were not significantly different. Subjects in the CR versus CR plus D conditions lost 9.6 [+ or -] 6.5 versus 10.8 [+ or -] 5.9 kg (p = 0.56) and 9.0 [+ or -]3.8 versus 10.1 [+ or -] 3.6 kg body fat (p = 0.37).
These finding suggest that a high-dairy calcium diet does not significantly improve weight loss beyond what occurs with a standard calorie restricted diet.
J. Harvey-Berino, B. Gold, R. Lauber, et al. The impact of calcium and diary product consumption on weight loss. Obes Res; 13:1720-1726 (October 2005). [Correspondence: Jean Harvey-Berino, Department of Nutrition and Food Sciences, University of Vermont, 315 Terrill Hall, 570 Main Street, Burlington, VT 05405-0148. E-mail:
Jean-Harvey-Verino@uvm.edu].