FDA

Exercise, Weight Loss, Protein and Calories

In a study was designed to measure nitrogen balance, there were some interesting incidental findings regarding exercise, weight loss, calories and protein. (1) Researchers recruited 22 fit males for a 12 day study. Unlike most studies of this type that depend on questionnaires to track unsupervised periods, these volunteers spent 24 hours a day in a research dormitory. The first 4 days confirmed the caloric intakes and energy expenditures that were established prior to the experiment. They were then divided into 3 groups and for 7 consecutive days their activity levels were increased over individual baselines by 1000 calories (done in 15 minute blocks of different exercises throughout the day). See Figure 1.

Figure 1 - Energy Groups
-Neutral Energy group (NE) – Consumed 1000 extra calories a day above their established baseline of ~3500 calories a day with a protein intake of 1.0 grams per kilogram of body weight per day (g/kg/bw/d.)
-Low Energy group (LE) – Normal diet of ~3600 calories with 1.0 g/kg/bw/d of protein.
-Low Energy High Protein group (LEHP) – Normal diet of ~3900 calories with 1.8 g/kg/bw/d of protein.

The subjects in this study lost weight by burning more calories rather than eating fewer calories. Table 1 shows the low energy - high protein group lost less muscle, more fat and more weight than the low energy group (with identical calorie totals and activity levels) that contained less protein. This supports what we already know about the metabolic cost and muscle protecting effects of protein. (2)

The result ranges in table 2 show that not every subject in the low energy high protein group lost less muscle and more fat than every subject in the low energy normal protein group. And both tables show that every person in the neutral energy group also lost weight (the study was not mathematically designed for that to happen). Either the post exercise metabolic activity was higher or the caloric intake was lower than the researchers calculations, measurements and /or models indicated. Furthermore, even though the neutral energy group consumed less protein than the low energy high protein group did, the extra calories protected more muscle than the extra protein did.

In conclusion based on this small study, the low energy diet with higher protein did appear to increase thermogeneis and preserve muscle at the expense of fat compared to the low energy diet with normal protein levels. Conversely, the differences between the low energy groups were smaller than the differences between either low energy group and the neutral energy group. In other words, a calorie is not a calorie and does differ depending on its source - but - total calories still exert a larger influence than the total of a calorie source does. This not surprising and checking out the weight loss section in any bookstore proves it. Simply look around and you will see best sellers that advocate high protein, low protein, high carbohydrate, low carbohydrate, high fat, low fat and every combination in between. The reason so many seemingly contradictory approaches claim to be successful is because they are – as long as a person pays enough attention to follow the plan which, one way or another, prevent energy intake from exceeding energy output.

¹ Pikosky, M.A., Smith, T.J., Grediagin, A. et al Increased Protein Maintains Nitrogen Balance during Exercise – Induced Energy Deficit Med Sci Sport Exer 2008; 40(3) 505-512.

2 Halton TL and Hu FR The Effects of High Protein Diets on Thermogenesis, Satiety and Weight Loss: A Critical Review. J Am Coll Nutr October 2004; 23 (5) 373-385.

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