Monday, October 17, 2005

Protein and Satiety

As a nation, we seem to always be seeking the "easy fix" or the "next big thing" when it comes to losing weight, so I wasn't surprised by the headline "Protein is the new diet hook" in yesterday's USA Today.

The article reviewed recent data from a study out of Australia that was presented this weekend at the North American Association for the Study of Obesity (NAASO) conference. The study was published in the Journal of Clinical Endocrinology & Metabolism in September and found that higher protein intake increased satiety in those on a weight-loss diet.

So, let's take a look at the study.

The researchers followed 57 overweight/obese, hyperinsulinemic individuals (25-men and 32-women) for 12-weeks of weight loss and 4-weeks of weight maintenance. They were randomized into two groups and each group was given a 1,400-calorie-per-day diet to follow that was either "high protein" or "high fat."

It is here that it is important to understand the macronutrient mix they were allowed:
  • Group 1 - High-Protein - 1400 Calories per Day
    29% Fat, 34% Protein, 37% Carbohydrate
    406 fat calories, 476 protein calories, 518 carbohydrate calories
    45g fat, 119g protein, 129.5g carbohydrate
  • Group 2 - High Fat - 1400 Calories per Day
    45% Fat, 18% Protein, 37% Carbohydrate
    630 fat calories, 252 protein calories, 518 carbohydrate calories
    70g of fat, 63g protein, 129.5g carbohydrate

Both groups lost about the same amount of weight and improvements in fasting and postprandial insulin and glucose occurred independently of diet composition. The big difference between the two groups was the decreased hunger reported by those on the "high protein" diet.

While the results are indeed interesting and show that protein is a factor in satiety, the researchers missed opportunities to explore how macronutrient mix does affect appetite, weight loss and markers like insulin and glucose. The researchers also failed to provide adequate nutrients to the participants.

In this study, one of the two groups was protein deficient.

Yes, I said it - 63g of protein each day is simply not enough protein intake for an obese individual and that is what the "high fat" group had for their protein intake. In fact, it is barely enough protein for a normal weight, average height woman....for an obese male or female this amount of protein is deficient - there's no way around it.

In this study, the other group was fat deficient.

Yes, I really said that too - in the group eating 29% fat calories, their fat intake was restricted to just 45g per day at 1400 calories per day. It is safe to assume that this level of fat intake failed to meet or exceed their essential fatty acid requirements for each day.

So what we really have here in this study is a comparison of two nutritional deficiency diets. Neither is healthy or should be recommended.

I've said it before and I'll say it again - the key to weight management and health is nutrient-density and adequate calories to support basal metabolism during weight loss. Until researchers shift their focus from percentage of calories in the diet of macronutrients - fat, protein and carbohydrate - we will continue to fail in our dietary recommendations and fail to provide the general public with usable information to not only lose weight but maintain their weight loss and optimize their health in the long-term. Until researchers address the real calorie needs for the overweight or obese and stop placing these individuals on hypocaloric starvation level diets, weight gain after weight loss is inevitable and the obesity epidemic will continue to be problematic in our country.

I would bet money that every last person in this study gained back the weight they lost within the 90-days following the study end date. Why? They weren't given the tools to eat a nutrient-dense diet for the short or long-term.

1 comment:

  1. great post on an overhyped and widely misunderstood topic. I have book marked your site