JENNIFER E SEYLER¹*, DONALD K LAYMAN²
*Corresponding author
1. Current Lifestyle Marketing 111 E Wacker Drive, Floor 10 Chicago, IL 60601, USA
2. University of Illinois at Urbana-Champaign 260 Bevier Hall, 905 South Goodwin Avenue Urbana, IL 61801, USA

Abstract

Obesity is a world-wide epidemic costing billions in health care each year. Research demonstrates that the macronutrient composition of a calorie-controlled meal plan plays a significant role in obesity treatment. Nutrition research suggests that shifts in the American diet to consumption of a high carbohydrate, high glycemic, low protein diet reduces satiety, leads to excess energy intake, and forces the body to utilize insulin to store excess glucose and fat. This dietary pattern also reduces protein metabolism that is essential for repair and protection of muscle function. There is increasing evidence that the quantity and quality of protein are of critical importance in correcting this metabolism and body composition. The proportion of protein and carbohydrates in the diet influences muscle protein synthesis, muscle energy regulations, stability of blood sugar, satiety, and ultimately body composition.
This review summarizes the new research suggesting that the conventional RDA guideline for dietary protein, which recommends as little as 55 grams per day may be inadequate to achieve the full functional value of protein in the diet. New research points to redefining adult protein needs based on meal requirements of approximately 30 grams of high quality protein necessary to provide adequate essential amino acid leucine amounts to maintain muscle size, function, and glucose metabolism.

INTRODUCTION

Nearly one-third of the American population is currently obese, and an estimated $69 to $117 billion per year is spent on associated treatment. This article discusses the interactions of dietary protein and carbohydrates in blood glucose regulation and its effects on body composition and weight loss.

BLOOD GLUCOSE REGULATION
It is well known that eating carbohydrates produces a rise in blood glucose levels, resulting in increased insulin secretion and a decrease in glucagon [1]. This, in turn, sets off a cascade of events, including: increased glucose uptake [2], glycogen synthesis [3] and decreased/suppressed hepatic glucose production [4] and fat storage.. Within 2 to 3 hours after a meal, dietary glucose is either stored as glycogen or fat or oxidized for energy [5]. Likewise, dietary fat is either used for energy or stored; and protein is either used to make new proteins or made into glucose [6].
In the fasted state, or post-absorptive periods between meals, the exogenous glucose is not available and the body relies on endogenous sources to maintain blood glucose, i.e., glycogen breakdown and gluc ...