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The purpose of this study was to:

• determine the effects of dietary calcium on body weight and fat loss in  humans, secondary to energy restrction diets producing and energy deficit of 500 kcal/day
• compare effects of supplemental calcium carbonate and dairy calcium in augmenting weight and fat loss in humans  

Participants were obese, had low calcium diet (500-600 mg/day, as assessed from food frequency and diet history) at study entry, experienced no more than 3-kg weight change over the preceding 12 weeks, and had no recent 12-week changes in exercise frequency or intensity.

 

Participants were excluded if they:

• required use of oral antidiabetic agents or insulin
• used obesity pharmacotherapeutic agents and/or herbal preparations intended for obesity management
• had a history of significant endocrine, hepatic, or renal disease
• were pregnant or lactating
• suffered any form of malabsoprtion syndrome 

Recruitment Not indicated

Design In this randomized, placebo-controlled trial participants were studied for a 2-week period for baseline measures and then were randomized to one of the following for 24 weeks: (a) control diet with a 500 kcal/day deficit) with 0-1 servings of dairy products/day, 400-500 mg calcium/day and a daily placebo supplement; (b) a calcium-supplemented diet identical to control but with placebo replaced by 800 mg calcium (as calcium carbonate) to bring total dietary calcium to 1200-1300 mg/day or (c) a high-dairy diet (placebo supplemented) providing a 500 kcal/day deficit and containing 3 daily servings of dairy products, to bring total calcium intake to 1200-1300 mg/day.  

Blinding used (if applicable) Not indicated

Intervention (if applicable) Participants were studied for a 2-week period for baseline measures and then were randomized to one of the following for 24 weeks: (a) control diet with a 500 kcal/day deficit) with 0-1 servings of dairy products/day, 400-500 mg calcium/day and a daily placebo supplement; (b) a calcium-supplemented diet identical to control but with placebo replaced by 800 mg calcium (as calcium carbonate) to bring total dietary calcium to 1200-1300 mg/day or (c) a high-dairy diet (placebo supplemented) providing a 500 kcal/day deficit and containing 3 daily servings of dairy products, to bring total calcium intake to 1200-1300 mg/day.  Diets for treatment groups were constructed to provide comparable levels of macronutrient and fiber to approximate average consumption in US (fat approximately 35% of toal kcal, CHO approximately 49%, protein approximately 16%, and fiber 8-12 g/day). Nutritional supplements weren't permitted, and caffeine intake was maintained at a constant level. Participants on the high calcium and high dairy diets had significantly greater initial body fat (kg) levels (48.4+5.3 and 50.7+5.0, respectively) than control (low calcium) participants who had a mean initial body fat level of 59.4+4.7 kg. There was no significant difference betwee-group differences in initial body weight, initial trunk fat, or initial waist circumference.   

Statistical Analysis Multivariate ANOVA using SAS was used was evaluate repeated measures and independent group comparisons. Only participants who completed the study were included in analyses. 

 

Timing of Measurements Participants received individual instruction,counseling, and assessment from study dietitian re:dietary adherence and development and reinforcement of strategies for continued success. Diets were monitored weekly. Participants complted daily diet diaries throughout study, with compliance assessed weekly. Physical activity and tobacco use were maintained at baseline levels throughout study. Body weight and waist circumference were assessed weekly. Body fat, fasting insulin, glucose, fasting plasma lipids, and blood pressure were meaured at baseline and at weeks 12 and 24.

Dependent Variables

• Initial Body weight and BMI -measured using a calibrated scale (with height measured with a wall-mounted stadiometer). Participants wore street clothes with no outerwear or shoes. BMI was calculated using standard equation (kg per meters squared).
• Waist circumference-measured in standing position, with measures obtained midway between lateral lower rib margin and iliac crast. Measurements were taken midexhalation with average of 2 readings recorded.
• Total fat mass, % lean and fat mass-measured using DXA at baseline and at weeks 12 and 24. Instrument was calibrated and a spine phantom was assessed daily to determine whether any drift had occurred. 
• Blood pressure and heart rate-assessed with participant seated in an upright position in a chair for at least 5 minutes with arm supported at heart level. Blood pressure was assessed using an appropriately sized cuff and standard, calibrated sphygmomanometer on same arm for each measurement. Two readings, at least 1 minute apart, were taken and averaged.
• Glucose, insulin, and leptin-a standard 75-g oral glucose tolerance test was administered at baseline and weeks 12 and 24 or study, with blood sampled for glucose and insulin at 0, 15, 30, 60, 90 and 120 minutes. Plasma glucose was assessed using a glucose oxidase method and insulin and leptin using standard, commercially available radioimmunoassay kits.
• Fasting lipids-cholesterol, LDL, HDL, and triglycerides were measured using standard clnical techniques.

Independent Variables

Diet/Dietary Intake (control, high-calcium, or high-dairy diet)-dietary intake was measured using daily diet diaries completed throughout study, with dietitian providing pre-study training and measuring compliance throughout study.  

 

 

Initial N: 41 otherwise healthy, obese young adults

(Attrition (final N): 32 ( two men and 7 women did not complete the study)

Age: Age ranged from 18-60 when initially enrolled. Among completers, mean age was 49+6 years (N=32). There were no significant differences in completers vs. non-completers for any parameter studied. 

Ethnicity: Not indicated

Anthropometrics: Participants had an initial BMI of 30-39.9 (mean BMI was 34.9+4.3 among completers), a low calcium diet (500-600 mg/day, as assessed from food frequency and diet history) at study entry, no more than 3-kg weight change over the preceding 12 weeks, and no recent 12-week changes in exercise frequency or intensity. Mean values among completers (n=32) of the study were: systolic blood pressure 130+10 mm Hg, diastolic blood pressure 79+8 mm Hg, LDL cholesterol 140+32 mg/dL, HDL cholesterol 45+11 mg/dL, and triglycerides 133+52 mg/dL.  

Location: University of Tennessee

 

1. All participants lost body weight and body fat due to the daily kcal deficit of 500 kcal/day. However, both weight and fat loss were markedly increased on the high-dairy diet with intermediate (but still significant) effects on the high calcium diet. Participants on the low-calcium control diet lost 6.4+2.5% of their body weight, which was increased by 26% (to 8.6+1.1%) on high-calcium diet and by 70% (to 10.9+1.6%) on the high-dairy diet (P<0.01).
2. Fat loss followed a similar trend: participants lost 8.1+2.3% of their body fat on the low-calcium control diet, which was increased to 11.6+2.2% on the high-calcium diet and 14.1+2.4% fat loss on the high-dairy diet (P<0.01). Participants on the low-calcium control diet had significantly higher fat mass than the other 2 groups (P<0.05) and this group also lost the least amount of body fat during energy restriction.
3. Circulating leptin levels followed a pattern similar to that of body fat. All 3 groups showed significant reductions in plasma leptin levels (P<0.01), with participants on the high-dairy diet demonstrating a 51% decrease, vs. 19% and 33% in the low-calcium and high-calcium groups, respectively (P<0.01 vs. high dairy).    
4. Unexpectedly, there was a marked change in the distribution of body fat loss among participants. Participants on the low-calcium diet lost 5.3+2.3% of trunk (abdominal region) fat. This was increased to 12.9+2.2% on the high-calcium diet and 14.0+2.3% on the low-calcium diet (P<0.025 vs. low-calcium and high-calcium diets). As a result, fat loss from the abdominal region represened 19.0+7.9% of total fat lost on low-calcium diet, and this was increased to 50.1+6.4% on high-calcium diet (P<0.01) and 66.2+3.0% on high-dairy diet (P<0.01). These changes were reflected in corresponding differences in waist circumference changes (P<0.01).
5. Glucose tolerance did not differ significantly among groups at baseline. But after 24 weeks on the diet, the high-dairy group demonstrated a significant improvement in glucose tolerance while the other 2 groups exhibited no change (P<0.01).  Fasting glucose levels were not impacted by diet, but there was a 44% decrease in plasma insulin levels in participants on the high-dairy diet (P<0.01).
6. There were no significant effects of any of the diets on diastolic blood pressure or circulating lipids. The participants on the high-dairy diet exhibited a modest (4.8+2.1 mm Hg) decrease in systolic blood pressure (P<0.02).   

Increasing dietary calcium significantly augmented weight and fat loss secondary to energy restriction and increased % of fat lost from the trunk region. Dairy products exerted a substantially greater effect than supplemental calcium.

Industry:

National Dairy Council Commodity Group:

1. No information was provided about race or ethnicity.
2. Research was supported by the National Dairy Council.