A two-year study of the effects of different diets on weight loss was just published in the New England Journal of Medicine (Frank M. Sacks, MD, et al., Feb 26, 2009, pp. 859). One of the research sites was Brigham and Women’s Hospital locally. The results are of interest to us and reaffirm that calories unfortunately do count and that the Second Law of Thermodynamics still applies to humans.
Over 800 men and women (about 1/3 and 2/3) participated. The overall average age was 51, weight 207#, height 5’6″, typical of a substantially overweight group. At baseline, their reported diets averaged 2000 cal and 45% fat. They were assigned to one of four study diets, all with the same caloric content (targeted at 750 cal below their estimated caloric requirements) and apparently with a healthy food selection, and were offered regular group and individual counseling sessions (the groups met every 2 weeks, as does our OHC weight management group) to reinforce healthy food choices, exercise, and so forth. The diets were:
- Low fat (20%) with low protein (15%) and therefore high carbohydrate (65%)
- Low fat (20%) with moderate protein (25%) and the balance carbohydrate (55%)
- High fat (40%) with low protein (15%) and moderate carbohydrate (45%)
- High fat (40%) with high protein (25%) and therefore low carbohydrate (35%), getting toward South Beach range.
Weight loss was statistically the same in the 4 groups. For participants as a whole, maximum weight loss was about 13# at 6 months, began to slip at 12 months, and had receded to 9# by 24 months, meaning a group average weight still of 198#. About 1 person in 7 lost at least 10% of body weight (hence about 20#) and about 25 people in the group lost over 44#. Those who attended the majority of the counseling sessions did best, losing about 20#.
Observations on the Statistics
Some study data makes one wonder. For example, the reported average baseline food intake of the participants was 2000 calories, which hardly is consistent with average body weights of 207#, which probably again reflects how poorly people remember how much they really eat each day. However, the 40% fat intake (800 calories, or about 90 grams of fat daily) was not surprising. That’s how you get fat yourself.
The study diets were set at 750 calories below the person’s breakeven, which should therefore result in a weight loss of about 6# monthly, but the actual average weight loss of 13# at 6 months implies a true 260 daily calorie deficit. Restricting calories is hard.
As perspective on how overweight this group was, for someone 5’6″ tall (like the group average), a weight of 155# would give a BMI of 25, the maximum value that is considered a normal weight. Hence the study group was an average of at least 57# overweight, or well more than a third of their proper body weight. In the study, they ended up 9# down, or only 48# overweight. Think on that.
The first study takehome is that calories do count. We have known this scientifically for many decades, but somehow have to keep reproving the point. Food distribution matters insofar as a person is more likely to follow a diet that is tasty, interesting and consistently satisfying than one that is uninteresting or requires deprivation. Providing the diet is nutritionally sound and not extreme (the Twinkie diet, the grapefruit diet, the “induction” phase of the Atkins diet), the precise composition matters little. Have we heard these points made before in our meetings or in other writings in Orchard Health Care?
The second takehome is that losing weight is really difficult. Do you want to expend so much emotional energy and intellectual attention on a long-term basis to settle for an 9# weight loss as the best you can do?
Third, some people were able to do remarkably better. The 800 participants, most of whom managed a paltry weight reduction, included over a 100 who lost 20 to 40# or more and appear to have kept them off (although there aren’t really detailed data on these winners). So there is hope. Winning is possible.
Last, the individual and group meetings for advice, counsel and motivation were clearly effective. Each meeting in the 2-year study was associated with about a 1/2# incremental weight loss. The more meetings, the greater the success. Regular meeting-goers averaged 20# losses. That provides an important validation of the importance of behavioral management of weight loss and the role of meetings such as our biweekly evening gatherings to help each other succeed.
Calories count. Losing is really tough. Group support makes individual efforts to lose weight easier and more effective. I think our members want to win this battle. So let’s make as good use as we can of our alternative Tuesday evening gatherings.