Metabolic Hype. Part II

Most webaloney contains a smattering of good advice and a raft of utter nonsense. Yes, we should prevent dehydration by drinking pure water, but drinking “miracle” drinks will not improve your metabolic fitness.

1. Caffeine is not a metabolic “booster” except for the limited advantage it affords in endurance sports. In training or competitive events lasting more than 3 hours, caffeine can improve fatty acid utilization, thus sparing glucose to the final sprint. This is used by Red Bull, 5 Hour Energy et al to claim their products enhance human performance. But when these products are tested under normal exercise and sports conditions, there is no benefit compared to placebo.

REF: Nutrients. 2013 Jun 6;5(6):2062-75. doi: 10.3390/nu5062062.

The effects of caffeinated “energy shots” on time trial performance.

Schubert MM1, Astorino TA, Azevedo JL Jr.

PS. In training endurance athletes, I observed that those using caffeine had a greater risk for post-event dehydration and longer recovery time. Thus the “benefits” of caffeine should be weighed against the risks.

2. A post this week claimed that a special herb tea improves metabolism by stimulating bile production. Assuming this is even true, the only possible benefit might be increased absorption of fat; certainly not increased utilization of fat to create energy.

3. Another article promoted a kale/ spinach green smoothie as a metabolic booster. But daily consumption of raw kale green drinks can actually reduce metabolic fitness due to possible effects on thyroid function. There is no doubt that kale is a superfood, but should be used as PART of a highly varied natural foods diet. A one cup serving of lightly steamed kale that you would eat is about 65 grams. This kale spinach smoothie used 3 large stalks of kale, which is about 168 grams. On a daily basis, that amount could have a negative effect on thyroid function if you are low in iodine. Ironically, the people quaffing kale smoothies may also be avoiding iodized salt and seafood, thus increasing their risk for reduced metabolic fitness.

4. Protein shakes. I like protein shakes because they support muscle mass. But the claim this week that protein shakes boost metabolism was a bit perplexing, in that the claim was “The body has to work harder to break down protein compared to carbs and fats. This extra work allows metabolism to be boosted, making way for weight loss.”

This is pure webaloney, akin to the “negative calorie” argument used to promote certain diet foods, where the food supposedly requires more energy to digest than it provides.

OK. Nutrition Detectives. There is ONE legitimate negative calorie beverage. Name it to be eligible for fabulous prizes.


The Metabolic Makeover
Stephen Cherniske, M.S. & Natalie Kather, M.D.

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