Effect of calcium and dairy foods in high protein, energy-restricted diets on weight loss and metabolic parameters in overweight adults

Abstract

OBJECTIVE:To compare the effects two high-protein (HP) diets that differ in dietary calcium and protein source on weight loss, body composition, glucose and lipid metabolism, markers of liver function, fibrinolysis and endothelial function and blood pressure. DESIGN: Randomized, parallel study (12 wk of energy restriction, 4 wk of energy balance) of high dairy protein/high-calcium (DP, 2400 mg Ca/d) and high mixed protein/moderate calcium (MP, 500 mg Ca/d) diets (5.5 MJ/d, 34% protein, 41% carbohydrate, 24% fat). SUBJECTS: In all, 50 healthy, overweight (age 25-64 y; body mass index 25-35 kg/m 2 ;) males (n ¼ 20) and females (n ¼ 30). RESULTS: Loss of total weight (À9.773.8 kg), fat mass (À8.370.4 kg) and lean mass (À1.670.3 kg) were independent of dietary group. Improvements in fasting insulin, lipids, systolic/diastolic blood pressure, and markers of liver function, fibrinolysis and endothelial function were independent of dietary intervention. CONCLUSIONS: Increased dietary calcium/dairy foods in an energy-restricted, HP diet does not affect weight loss or body composition. Weight reduction following increased protein diets is associated with beneficial metabolic outcomes that are not affected by protein source.

Effect of dairy consumption on weight and body composition in adults: a systematic review and meta-analysis of randomized controlled clinical trials

“…Besides restriction of energy intake to a fixed value, these two studies had some other distinct features. The study by Bowen et al 33 compared a high-dairy diet with a high-protein diet, whereas those we included in the meta-analysis used a high-dairy diet versus diets with the same amount of protein. Another RCT done by Zemel et al 41 was a two-phase RCT that had 3 months of energy restriction to 1200--1500 kcal per day and a 6-month maintenance phase.…”

“…We found that two papers, 33,41 which administered energy restriction, had confined the energy intake into a defined certain value in both intervention and control groups, whereas other studies restricted the energy intake of participants to the amount of 500 kcal less than their computed daily energy requirement. Because restriction of energy to fixed values can directly affect weight change, 33,41 we preferred not to include the results of these two studies in the systematic review and meta-analysis; however, findings from the maintenance phase of study done by Zemel et al 41 were included in our systematic review. Besides restriction of energy intake to a fixed value, these two studies had some other distinct features.…”

Dairy protein and leucine alter GLP-1 release and mRNA of genes involved in intestinal lipid metabolism in vitro

“…Total RNA (1 μg) was reverse-transcribed using Superscript II Reverse Transcriptase (Invitrogen, Carlsbad, CA, USA) with oligo-d(T) [12][13][14][15][16][17][18] as primer. After reverse transcription, the same batch of diluted cDNA was subjected to real-time polymerase chain reaction (PCR) to amplify target genes.…”

“…As regulators of protein metabolism, branched-chain amino acids (BCAAs; leucine, isoleucine, and valine) have also been reported to improve glucose and cholesterol metabolism [13,14] and control appetite [15]. A study by Bowen et al [16] suggested that the protein component of dairy appears to be more important for weight loss than calcium in over-weight adults. Therefore, likely candidates for these additional effects of dairy are casein and whey and its high concentrations of BCAAs.…”

Relationship Between Changes in Fat and Lean Depots Following Weight Loss and Changes in Cardiovascular Disease Risk Markers

“…Seven published weight‐loss studies from our research group,19, 20, 21, 22, 23, 24, 25 which had a total body dual‐energy x‐ray absorptiometry scan at baseline and 12 weeks and had a minimum of measures of glucose and lipids at each time point, were combined electronically for analysis. All studies followed a similar protocol, with variations in the amount of protein, carbohydrate, and fat, and had similar amounts of weight loss.…”