Adiposity (too much fat in the body) is not the same thing as overweight. Many folks rely on body mass index as a measure of current state, unfortunately, BMI doesn’t distinguish between these two conditions. Further, both conditions MAY present health risks, depending on the amount of body fat a person carries. (Most people don’t suffer ill effects from too much muscle!) An important recent study examined the changes associated with various protocols among obese women. The results are pertinent to anybody considering a program or writing a program for somebody else.
Researchers investigated the effect of diet alone, diet + moderate physical activity, and diet + intense physical activity. Sixty previously sedentary women, mean age = 42.9 yoa, weight = 182 lbs, and 42% body fat, were randomly assigned to one of three groups. All three groups at a “Mediterranean Diet” (25-30% protein, 40-45% carbohydrates, 30-35% fat); dietary protein was set at 1.8 g/kg of body mass; no vitamins or supplements were used; and all participants ate a hypocaloric diet with a reduction of 500 kcal/day. All groups received information and support regarding diet and exercise. The control group (CT) walked 30 minutes/day (roughly 5,000 steps/day) at minimal intensity; the moderate physical activity group (MPA) had a goal of 10,000 steps/day - roughly 60 minutes at a moderately vigorous intensity level (60% VO2max); the intense physical activity group (IPA) participated in three sessions/week of a pre-choreographed strengthening session performed with weights at a 60-80% of maximal strength level in addition walking on the other days of the week using the moderate group plan. The study lasted six months.
Results
At the three-month mark all three groups lost a similar amount of body mass (12.3 lbs; 16.5 lbs; 15.5 lbs). However, body fat changes (-3.96% v -6.21% v -10.19%) and muscle mass changes (-6.2 lbs v -7.3 lbs v -0.22 lbs) were significantly different. Total weight loss at the six-month mark was -13.9 lbs v -23.1 lbs v -22.2 lbs. The CT group actually gained back some body fat (0.5%) while the MPA lost an additional 4.2% and the IPA an additional 6.2%. The CT group also lost an 1.8 lbs of muscle mass while the MPA group sustained no more appreciable loss and the IPA group gained 2.2 lbs of muscle!
The results are consistent with other research in the field therefore some take away points are important:
Diet alone is an effective weight loss but not necessarily a fat loss tool in the short-term (3 months).
The efficacy of diet alone after three months is not good and may result in a return of body fat.
Moderate physical activity is an important component of a weight loss plan.
Intense strength training in conjunction with moderate aerobic activity was the only protocol that produced fat loss AND muscle mass gain.
Intense strength training with moderate aerobic activity and a hypocaloric diet may not result in greater weight loss (nor substantial changes in BMI) BUT it will likely have a more positive effect on fat:lean body mass ratios.
There is more to be gleaned from the study which is available here.