Thursday, December 15, 2011

Calories and Diets in the Lab

I was reading an article earlier this week which referred to the research referenced at the end of this post.  I was curious about the study because it compared the weight loss results of three or four groups.  I searched for the study itself so that I could see the actual requirements for each of the groups.  Here are the 4 categories that intrigued me:

  1. Consume 25% Less Calories per day
  2. Consume 12.5% Less Calories per day and Increase Physical Activity by 12.5%
  3. Consume a Very Low Calorie Diet (VLCD)
  4. Consume as usual (control group)
Instead of going too much into the study, I want to share what these group assignments  meant for the people involved in the research. I think the information is relevant and interesting to people who "cut their calories."  Ironically, it was the VLCD group that got my attention.  The article I was reading mentioned 25% and 12.5% reductions but did not give any clue as to what was meant by very low calorie. 

The scientists were able to determine the near exact total energy expenditure (TEE) and total energy intake (TEI) of the participants when they signed up for the project.  This was a small study.  The participants stayed overnight (once or twice) in the lab and ate all their meals according to a strict protocol in the weeks that followed (except the control group).  Each of the reduced calorie groups had a different caloric plan, based on their individual baseline and metabolic (energy burn) needs.   

For the purpose of an example, let us say that the TEI of a person in group 1 was 1900 calories at the start of the study. That means they would then eat 475 calories less (25%)or 1425  calories a day.  I believe the person did this until they lost a certain amount of body weight and then the calories were adjusted in order to maintain the new weight.  It could be that the end caloric intake was 1600 a day.
Take a similar person in group 2.  They would eat about 235 calories less than 1900 and would have to burn the other 240 calories in exercise.  The heavier a person is, the less time they would need to burn those calories, but according to the article, the average time spent walking (or something similar) per day was between 45 and 50 minutes.  This group had to exercise 5 days a week and 3 of those days had to be under the supervision of a research assistant.
Group 3 got the worse of it to be sure.  They were given 890 calories a day until they lost 15% of their body weight.  After which, whatever calorie amount was needed to maintain their new weight was adopted.
So - all this to say that in the 24 weeks for which results are provided up until week 24 when groups 1 and 2 merged, the diet only group lost more weight than the diet and exercise group.  
The VLCD group -the 890 folks- lost the most weight and lost it the fastest, but it is unrealistic for ANYONE in a "free living" environment to manage a diet that extreme. I would not have known if the VLCD was feasible if I had not tracked down the study protocol. 

If you are interested in the study, the information to access it is below.

Effect of 6-Month Calorie Restriction on Biomarkers of Longevity, Metabolic Adaptation, and Oxidative Stress in Overweight Individuals: A Randomized Controlled Trial
Leonie K. Heilbronn, Lilian de Jonge, Madlyn I. Frisard, JAMA. 2006;295(13):1539-1548.

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