The role of phosphorus in diet induced thermogenesis of both lean and obese subjects -

Abstract

The problem of both overweight and obesity is becoming globally spread and it is one of the main health issues nowadays. Even though genetics certainly plays a role, weight gain is eventually the result of a failure in the balance between energy expenditure and energy intake. We can get energy expenditure by summation of the resting metabolic rate, thermogenesis and energy expended on physical activity. Diet induced thermogenesis (DIT) represents the main form of thermogenesis in human, it accounts for 5-15percent of total energy expenditure and is primarily related to ATP production that is utilized for the digestion, absorption, transport and storage of food. The macronutrients have variable thermic effect (fat 0-3percent, carbohydrate 5percent-10percent, and protein 20percent-30percent). Moreover, this thermic effect is valued to account for 5percent to 15percent of total energy expenditure. The production of ATP mainly depends on hormonal (mainly insulin) factors and on phosphorus availability, which is affected by dietary intake. ATP production in the human body depends upon adequate sources of phosphorus (P) that can be distorted by the digestion and absorption of high-carbohydrate–low P food. Mainly due to the increase in insulin release, that simultaneously stimulates peripheral uptake of P and the phosphorylation of many compounds. Actually, this creates a competition for P that compromises its availability for ATP production, which is thought to be translated into low DIT. Studies have shown that diet induced thermogenesis is low among obese subjects as compared to lean subjects. Our objectives are to measure: Experiment 1. The involvement of phosphorus in DIT among lean subjects Experiment 2. The involvement of phosphorus in DIT among obese subjects. Subjects will be given oral high carbohydrate meal with or without Phosphorus (potassium phosphate). Postprandial thermogenesis will be measured. The primary outcome variables are thermogenesis. We hypothesized that phosphorus ingestion will increase thermogenesis of subjects. A cross