Short Term Splurge – Long Term Fat

What the end-of-year round of holiday parties means for many people is a good month of overeating on foods that are high in fat, calories and salt. And of course we know what the outcome is of such overeating: holiday weight gain followed by a New Year's resolution to lose weight and exercise.

A group of Swedish researchers looked at the long term effects of such overeating in a small study that was just released by the journal Nutrition & Metabolism (www.nutritionandmetabolism.com/content/7/1/68). They recruited 18 healthy, normal-weight young people whose average age was 26. At the start of the study, the researchers used sophisticated equipment to measure each participant's Basal Metabolic Rate and their body fat vs. lean body mass. The participants met with a dietitian to assess their current diet and wore a pedometer to measure the average number of steps they normally took each day - their activity level.

During the study itself, the young people were instructed to double their current caloric intake for one month by eating at least two meals a day at a fast food restaurant. If they for some reason couldn't eat at a fast food restaurant, they were told to choose foods that were high in protein and saturated animal fat - with the priority being eating the required number of calories. They were also instructed to refrain from taking more than 5,000 steps per day, which is considered clinically sedentary.

After thirty days all of the young people had gained weight - about 15 pounds, on average - and this weight was gained in both lean muscle mass and body fat.

Six months later most of them had lost about 2/3 of what they'd gained. What's interesting is that they still had more body fat than they did before the overfeeding - meaning that they'd lost more lean body mass than they lost body fat.

12 months later they participants' weights were still up, on average, about 3.5 pounds over their starting weight. They had the same amount of non-fat body mass that they did before the overfeeding, but more more fat mass - just about exactly the 3.5 pounds they'd kept on.

After 2 and a half years their weight was up almost 7 pounds over the starting weight, while a comparable control group (who had simply continued their normal diet and exercise level during the study month) had maintained their starting weight.

What this means for you

Overeating unhealthy food on a regular basis for even a comparatively short time is likely to increase your body fat over the long term, even if you lose the excess weight. And we know that higher body fat is linked to a greater risk of diabetes, heart disease, cancer and other health risks. We would also be interested to know if eating home-cooked meals, instead of fast food, would have had the same effect.

There are two take-home messages here. First, and most obviously, don't take "the holiday season" as a license to throw out your healthy eating habits and splurge for a month. Second, don't let one special occasion's indulgence derail your healthy eating habits for more than one meal. Instead, eat that great special occasion meal, enjoy it, don't feel guilty about it, and continue your regular healthy eating habits at the very next meal.

First posted: September 8, 2010