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A simple pre-workout ritual that increases fat loss by 100 calories.

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Jade Teta ND, CSCS

A new study in this month’s issue of Medicine and Science in Sports and Exercise (May 2010) shows how a simple preworkout ritual can increase your fat-calorie “afterburn” by almost 100 calories. As we learn more about the science of nutrition and the synergistic effects of diet and exercise, it is becoming more clear that calories are not all there is to body change.

Protein and carbohydrates have very different metabolic signals despite being equal in calories gram for gram (i.e., 1 g of protein or carbohydrate has 4 calories). Protein however stimulates the release of both glucagon and insulin while carbohydrate signals insulin release exclusively. Protein is also a major building block of muscle tissue, carbohydrate is not. The hormonal effect is just as important as calories if you want the calories you do burn to be fat. In this study, participants were given one of two supplements 20 minutes before a resistance training workout. The supplements were nearly identical in calories yet exact opposites in their protein carbohydrate ratios. Here is how the two supplements broke down:

Supplement 1= Protein Supplement (Designer Whey Protein)= 18g Protein, 2g Carbohydrate, 1.5g Fat = 93.5 calories

Supplement 2= Carbohydrate Supplement (Nesquick)= 1g Protein, 19g Carbohydrate, 1g Fat = 89 calories

The workout consisted of nine weight training exercises. Each exercise was done for 4 sets of 10 reps with ~73% of a 1RM (RM stands for rep max. A 1RM is a weight you can do only once with the second rep being impossible). The researchers wanted to see how each supplement would impact the known metabolic after-burn generated by resistance training workouts. Previous research had hinted there was an effect of pre-workout supplementation. However, none of the older studies went past a few hours to measure the long-term effects. This study measured the impact for 48 hours.


Both groups, the carbohydrate group and the protein group, experienced the expected increased metabolic rate at both 24 and 48 hours after exercise ended. In addition, the respiratory exchange ratio (RER), a measure of how many fat calories you burn vs. sugar calories, was decreased in both groups. A decreased RER signals a greater utilization of fat vs carbohydrate for energy. This means the weight training sessions caused increased fat loss in both groups after the exercise session. This increased fat burn lasted for 24hr in both groups.

But, what the researchers really wanted to know was if protein or carbohydrate taken before the workout would impact the metabolic after-burn. Would it increase it, decrease it, or create no change? When the results were analyzed, it was shown that the protein supplement taken 20 minutes before resistance training created a significantly greater metabolic response than the carbohydrate. The magnitude of this response was measured to be 5% greater. In real world terms, this equates to ~90 more calories burned during recovery and as a result of including a small amount of protein before the workout.


This study actually confirms what other studies have hinted at for awhile. This was the first study to measure the effect for a full 2 days. Weight training in general has a pronounced metabolic effect that can cause elevation in metabolism lasting between 24 and 72 hours. Your choice of pre and post workout nutrition can enhance this effect or blunt it. Protein seems to be working through several mechanisms. The researchers speculate its action is epigenetic, meaning it interacts with cellular machinery that controls gene expression, both directly and indirectly via hormonal effects. Whey protein in particular is rich in branched chain amino acids (BCAA) that interact with a cellular signaling pathway call mTOR that regulates protein repair in damaged muscle. This process requires a large amount of energy and is believed to be the major reason intense resistance exercise has such a prolonged metabolic effect.

In addition, whey protein is able to lower cortisol while optimizing growth hormones. While some cortisol during the workout is necessary and helpful for fat loss, too much can result in muscle loss and inhibition of repair from exercise. The unique timing of a protein rich meal before weight training seems to optimize the hormonal ratios for increased recovery and elevated metabolism. While this study did not get into it, a controlled carbohydrate intake may be key to optimizing the effect of protein. Pre-workout nutrition for fat loss and muscle gain may be best when carbohydrates are avoided. Post-workout carbohydrate intake is more beneficial for muscle building, but too much may slow fat loss.

Based on this study, 20g of whey protein taken 20 minutes before a weight training workout can help you burn almost 100 extra calories in the 2 days after the workout while your simply sitting on the couch. This is a strategy we use, recommend, and have written about on this blog previously. This study demonstrates how useful it can be.

Here is a past blog on pre-workout nutrition where we cover this issue and more- http://metaboliceffect.wordpress.com/2009/03/07/should-you-workout-on-an-empty-stomach/

1) Hackney, et. al. Timing protein intake increases energy expenditure 24hr after resistance training. Medicine and Science in Sports and Exercise. 2010;42(5):998-1003.


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