Sunday, January 16, 2011

Calcium + Vitamin D for Breakfast Increase Dietarily Induced Thermogenesis and Fatty Acid Oxidation

Ever since the first studies suggested beneficial effects of dairy on weight loss, there have been a lot of trials that investigated the role of (supplemental) calcium in these contexts (mostly with discouraging results). A very recent study by Wendy and Soares (Wendy. 2011) took a very similar approach, but added vitamin D to the equation.

In their study, the scientists fed their 11 subjects (aged (mean ± SEM) 54 ± 1.2 y and BMI 31 ± 2.4 kg/m) a meal that was either high (HCT) or low (LCT) in vitamin D and calcium and measured diet induced thermogenesis (DIT), fat oxidation rates (FOR), serum leptin, subjective feelings of hunger/satiety hourly over a period of 8 hours. The results were far from earth-shattering; they could however solve the mystery of why most people find it easier to lose weight on a diet that is generally rich in dairy and calcium + vitamin D rich foods:
HCT resulted in lesser suppression of ΔFOR (p=0.02) and a significantly greater DIT (p=0.01). Further, the buffet to dinner interval was prolonged (p=0. 083) and reported 24h energy intake following this trial was significantly reduced (p=0.017). ∆leptin following HCT but not LCT was negatively related to 24 h fat intake (r = - 0.81, p=0.016).
So, the underlying mechanism is actually threefold and much different from the commonly heard hypothesis that dietary caclium would "bind fat in the intestine" and thus reduce caloric intake:
  1. greater postprandial fat oxidation
  2. significantly greater thermogenesis
  3. beneficial effect on leptin and thus decrease in hunger
What else would you want? If there was not the issue with lactose intolerance, eating as much dairy as possible could actually become a general recommendation for everyone who intends to lose weight and/or improve body composition