Really? Meat Causes Weight Gain?
Sunday, July 25, 2010
LifeTime WeightLoss in Nutrition, Protein, Research Studies, Tom Nikkola

A new study is making headlines and news spots claiming that meat consumption causes weight gain. Studies in recent years have shown that protein, including meat, consumption can have a positive effect on weight management, so the study making headlines comes as quite a surprise. Before you react too quickly and start eating bread and butter for each meal, the following provides more of the detail behind the study. This single published study should be weighed against the rest of the evidence on diet and weight management.

A group of researchers, publishing in the American Journal of Clinical Nutrition analyzed data from the EPIC-PANACEA project, an ongoing project looking at diet and lifestyle factors influencing health and fitness in Europe. The recent study looked at meat consumption and body weight over a five-year period. The study group included almost 374,000 people from 16 different locations. The study conclusion was that in this review, those who consumed the most meat (250 g/day) gained the most weight over a five-year period. The weight gain was approximately 2 kilograms (4.4 pounds). According to the researchers, this effect took place without a difference in calorie consumption compared to the lower protein intake groups. The bottom-line conclusion was that it appeared that eating more meat led to more weight gain without the extra meat adding extra calories to the individuals’ diets. Because meat is such a common source or protein in our diet, if there was a study that showed higher protein intake causes body fat gain, it would be something to react to. With the large amount of research showing how higher-protein diets support weight loss (which often don’t make headlines like this), how can this study show the opposite effect? We’ll take a look at some of the holes in the study that probably don’t make it into the story on the study.

Epidemiological Studies

This study was an epidemiological study, meaning it is intended to look at a variety of associations and find associations. As an example, if someone wanted to compare the number of American cars per household with the rate of obesity, they may find in the U.S., there are more American cars per person than anywhere else, and then conclude “driving American cars is associated with increased risk of obesity.” We know there is no “cause and effect” in a study like this as it is not designed for that. Yet, the news headlines make it sound as though this study showed increasing meat consumption increases weight gain, which, based on the study design, it cannot do.

Definition of Meat

Meat consumption in this study was considered to be poultry, processed meat or red meat. Interestingly, poultry consumption had the greatest association with weight gain, which makes the results seem even stranger, since it is usually leaner than meat or processed meat, and so it is less calorie-dense. The amount consumed by the group with the highest intake averaged about 250 grams of meat per day, or just under 9 ounces per day. A typical serving is 3-4 ounces, so it doesn’t make sense that 2-3 servings a day would cause weight gain. Because this was not a controlled study, we don’t know what type of meat the participants were actually eating – fatty cuts, lean cuts, fried, breaded, baked, grilled or what was added to it.

Participant Questionnaires

The study authors admit, another weakness in this study is that the study participants were only able to provide food questionnaire data, which often provides inaccurate results. In a more controlled study, study participants would be given their food. In controlled studies, increasing protein intake has had a positive effect on supporting weight loss. Of course, it is also necessary for maintaining or increasing lean body mass. In addition, weight was simply asked of the participants. It was not measured. Without ensuring weight was measured in a consistent way before and after, it makes the actual measures somewhat suspect.

Weight & BMI

Because this was a population study, it was not designed for weight management. It was designed to track weight and BMI over time. Body weight and BMI are not the most accurate measurements of one’s physical conditioning. Because we’re talking about 4.4 pounds of weight gain over five years time, it’s quite possible that the weight gain could be attributed to gains in lean body mass, or muscle tissue. It’s also possible that the consumption of other foods may play more of a role.  At any rate, because we don’t have body composition data, nor blood test results, the weight and BMI measurements have little meaning, especially because so many other studies show positive effects on LBM, body composition and blood values with increased protein consumption.

Summary

It is fascinating to see which published studies make news headlines and which do not. Oftentimes, it’s the epidemiological or population-based studies which make the news as their results seem to be “breaking news” – stories that seem to create some controversy. Unfortunately, they often serve to cause more confusion to the population than anything else. People may hear how a study like this is covered in the media and assume this is the final answer. In fact, in a case like this, the epidemiological study, which cannot in any way show a cause and effect relationship. On the other hand, there have been many other controlled studies that have showed increasing protein above the current levels of RDA have a positive impact on health and fitness. Of course, the right amount for each person varies so it’s best to talk with a Nutrition or Fitness Professional to know what’s best of you. There are a lot of other significant factors that affect weight gain such as excess processed carbohydrate intake, stress, digestive issues, sleep patterns, inflammation, insulin resistance, hormonal imbalances, lack of exercise, just to name a few. It’s best to put attention in those areas, which when corrected can often result in much more dramatic weight loss results.

 Reference:

  1. Vergnaud AC, Norat T, Romaguera D, Mouw T. Meat consumption and prospective weight change in participants of the EPIC-PANACEA study. Am J Clin Nut. 2010;92:398-407

This article is not intended for the treatment or prevention of disease, nor as a substitute for medical treatment, nor as an alternative to medical advice. Use of recommendations in this and other articles is at the choice and risk of the reader.

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