Weight loss 101
Apr 19, 2010
NUTRITION TOGETHER TUTORIAL
Weight Loss 101
Weight loss facts:
Excess body fat gain occurs (stored as fat in adipose tissue) when the number of calories ingested as food exceeds the daily energy requirements. When energy intake (food) is less than energy output (total daily energy expenditure or TDEE) the body will obtain its required calories from its energy stores and weight and fat will be reduced.
There are three ways to lose weight:
1. Reduce calorie intake below daily energy requirements.
2. Maintain regular food intake and increase energy expenditure through additional physical activity.
3. Combine both methods (ideal).
Sustained negative calorie balance: the key to loss of body fat
Creating a negative calorie deficit is essential for loss of body fat. Conversely, it is simply not possible to consume more calories than you expend and not gain weight, no matter what types of foods or food combinations you eat. This is the first law of thermodynamics (the conservation of energy law) in action: energy is neither created nor destroyed but transferred from one form to another.
Calories not only count but are the basis of promoting fat loss. A recent study published in the New England Journal of Medicine compared four different weight loss diets—all contained the same number of calories yet differed in amounts of macronutrients: Diet 1) low fat (20%) average protein (15%) 2) Diet 2: low fat (20%) high protein (30%) 3) Diet 3: high fat (40%) average protein (15%) Diet 4: high fat (40%) high protein (30%). After two years, all subjects lost approximately the same amount of weight, approximately 10 pounds. The authors concluded:
“In conclusion, diets that are successful in causing weight loss can emphasize a range of fat, protein, and carbohydrate compositions that have beneficial effects on risk factors for cardiovascular disease and diabetes. Such diets can also be tailored to individual patients on the basis of their personal and cultural preferences and may therefore have the best chance for long-term success.”
The take-away message: Reduced-calorie diets result in weight loss regardless of which macronutrients they emphasize. Hence, it’s all about sustaining a negative calorie balance, regardless of where the dietary calories come from. A moderate and sustained negative calorie balance will force the body to burn stored fat to make up for the energy deficit.
Creating an individualized and safe calorie deficit: how much is too much?
In the last tutorial we discussed estimating the number of calories your client needs to eat in a day to maintain their current body weight. It is well known that cutting the calorie intake too low slows the metabolic rate and promotes loss of both body fat and lean muscle mass. To target loss of body fat (and avoid loss of muscle mass), trainers need to avoid extreme cuts in a client’s daily calorie intake. Major health organizations recommend creating a moderate calorie deficit by reducing calorie intake by 500/day, and not more than 1000/day below the maintenance level. The golden rule of thumb is never to go under 1200 calories/day for any client. Ideally, creating a moderate daily deficit through diet while at the same time, increasing activity level, is the best strategy for targeting body fat.Many of your clients may balk at the number of suggested calories NT recommends for weight loss. Should this occur, you have the option of cutting the daily maintenance calories by 1000 (instead of 500) which will lower the client’s daily recommended food weight goal. Keep in mind, however, that many overweight clients like to believe that they eat less than they actually do. This has been scientifically shown time and time again… overweight people tend to radically underestimate their calorie intake and overestimate their physical activity.
Exercise and weight loss:
The American College of Sports Medicine position stand (based on the current scientific evidence to date): “Appropriate Physical Activity Intervention Strategies for Weight Loss and Prevention of Weight Regain for Adults,” states that participating in calorie-burning physical activity (such as walking) 225 to 420 minutes/week (~30 to 60 minutes per day, 7 days a week) results in clinically significant weight loss and a dose-response exists, meaning greater amounts of exercise result in greater amounts of weight loss. Furthermore, ACSM states that both physical activity and dietary restriction will result in similar amounts of weight loss only if they each provide the same level of negative energy balance. However, when combining exercise with diet, the exercise will only increase weight loss if the dietary restriction is moderate but not severe.
Translation: Putting your clients on a moderately restrictive (NOT severely restrictive) calorie diet and combining it with daily exercise is the ideal combination for promoting weight (fat) loss that can be sustained for the longterm.
Encourage DAILY exercise
A common mistake that some trainers make is to restrict the amount of extra exercise (cardio) their clients perform beyond the FT workouts. A recent study showed that FREQUENCY of exercise is most important for promoting fat loss. The study divided subjects into three exercise groups: less than 2 times per week, 2 to 3 times per week and 4 or more times per week. All three exercise groups lost body fat on average, however, only those who exercised 4 or more times per week achieved significant body fat loss during the 8 week study, approximately 13 lbs.
The take-away message: For the best results, it is important for trainers to encourage their clients to exercise additionally on their own to accumulate the desirable exercise frequency, i.e. at least 4 or more times per week and preferably daily.
In conclusion, the best approach to reducing body fat is to reduce calorie intake moderately and raise calorie expenditure by increasing the frequency or the intensity or the duration of aerobic exercise with an emphasis on frequency and duration for less fit clients. Combine the above two factors with an FT strength training program (at least 2 to 3 days a week) and you have the optimal prescription for getting your clients results that will last.
Frank M. Sacks, et al. “Comparison of Weight-Loss Diets with Different Compositions of Fat, Protein, and Carbohydrates.” N Engl J Med 2009;360:859-73.
American College of Sports medicine. “Appropriate Physical Activity Intervention Strategies for Weight Loss and Prevention of Weight Regain for Adults.” MEDICINE & SCIENCE IN SPORTS & EXERCISE DOI:10.1249/MSS.0b013e3181949333
Willis, FB, Smith, FM, and Willis, AP. “Frequency of exercise for body fat loss: a controlled, cohort study.” J Strength Cond Res 23(8): 2377–2380, 2009.