Thursday, November 4, 2010

Post-Exercise Energy Replenishment

    The association of exercise and weight loss and weight maintenance is intimately tied to thermodynamics, suggesting physical work is a key component to body fatness reduction. Anecdotal claims that exercise increases hunger and appetite making weight loss more difficult are not supported. In fact, contrary to these assumptions, several studies demonstrate that despite inducing a moderate energy deficit, an acute bout of exercise does not elicit compensatory responses in hormone driven hunger, appetite, or energy intake. This being said, many fitness enthusiasts consume food post-exercise to support their activity and as a reward for training. Conflict exists when post-exercise consumption negates the caloric expenditure needed for weight control. Part of the issue occurs because people do not understand healthy eating, nor do they grasp the difference between serving sizes and portions. Likewise, most people over predict the caloric expenditure associated with their training and do not need the recovery calories oftentimes recommended for athletes who are expected to meet high energy demands each day. This combination creates a weight management dilemma, as post-exercise consumption often exceeds expenditure and therefore slows or halts the weight loss process.
    General recommendations for post-exercise energy replenishment include up to 60 grams of carbohydrates and 20 grams of protein (3:1 ratio) immediately following exercise, with the caloric intake equivalent to the remaining deficit consumed within the next four hours. This makes sense for an individual who burns 400-700 calories every day through voluntary physical activity, needs the energy replaced for the next bout of activity, and is already of healthy weight. It is not warranted for a person who is overweight and attempting weight loss who burns between 150-300 calories per workout. The need for calories immediately following exercise still makes sense to some degree, but it is the caloric intake by quantity that needs to be managed. Based on the literature, a carbohydrate-protein mixture seems to best aid post-exercise recovery which explains the chocolate milk phenomenon. But many people think of chocolate milk as a dessert or sweet, making it undeserving of a post-workout meal. Ironically, smoothies seem to be categorized as a more healthy food even though they often contain more calories and more simple sugars.
    A homemade smoothie made of cut fruit, low fat milk and ice equates to about 150-200 calories per 8 ounce serving, not unlike chocolate milk. But a commercial smoothie contains many more calories, often due to both the size and the ingredients used. If made from real fruit, with 25 grams of protein powder, ice, and water the calories are much lower than those made from fruit syrup or fruit pastes and low fat (full sugar) frozen yogurt. Consumers are often sold on the terms natural, real, and organic but when applied to peanut butter and chocolate and hidden sugar those words still mean high calories. The same can be said for many of the protein-based energy bars. The average caloric range is 250-400 calories per bar which represents more calories than most people burn per weight training workout. Most of these products are designed for individuals looking to gain muscle weight, not weight loss, explaining why they are sold in gyms at point of purchase locations. 
    Post Exercise DrinkCaloriesFatSat. FatCarbsFiberSugarProteinCarb:Protien Ratio
    Protein Berry Workout 24 oz. (Jamba Juice)490 kcal1g0g99g7g81g23g5:1
    Planet Pro - Strawberry - 32 oz. (Planet Smoothie)460 kcal2g0g65g7g58g49g1.2:1
    The Hulk - Strawberry - 32 oz. (Smoothie King)1553 kcal48g19.5g241.5g12g187.5g40.5g6:1
    Muscle Blaster - 24 oz. w/ Splenda (Tropical Smoothie)284 kcal2.8g0g41g5g2g24g1.7:1
    P-Nut Power Shake - 12 oz. (Robeks)362 kcal0g16g39g4g23g11g3.5:1
    Low-Fat Chocolate Milk - 1 Cup (Commercial)158 kcal2.5g1.5g26g1.2g24.9g8.7g3:1
    Peanut Power - 32 oz. (Smoothie King)824 kcal33g6g111g9g89g23g4.8:1


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