Bariatric surgery appears to exert a favorable influence on family members of the recipient, leading to weight loss, healthier eating habits, and greater activity levels among adults and children residing with the patient, according to results from a prospective, longitudinal study in the October Archives of Surgery.

"Previous studies have shown that obesity may be a social contagion and that by associating with obese individuals, a person is more likely to become obese. Our study may demonstrate that bariatric surgery in selected populations can provide a reverse corollary and induce weight loss and healthy behaviors in people surrounding the patient," Dr. Gavitt A. Woodard said.

Dr. Woodard and her associates at Stanford (Calif.) University assessed weight and lifestyle changes in spouses, parents, and children residing with patients during the year after the patients underwent Roux-en-Y gastric bypass surgery. They enrolled 35 families, including 35 patients, 26 spouses, 3 grandparents, 6 adult children, and 15 children younger than age 18 years during a 2-year period.

Patients and family members were required to attend three preoperative educational sessions and five postoperative visits in which lifestyle modification was emphasized. A high-protein, high-fiber, low-fat, low-sugar diet was recommended for the patients, which advised six small daily meals comprising 200-300 calories and including 4-6 ounces of protein.

Lifestyle modification included daily goals of increased physical activity (10,000 steps per day), 8 hours of sleep, moderation of alcohol intake, and avoidance of watching more than 2 hours of television.

After 1 year, the study subjects were evaluated by a physical examination as well as a battery of validated questionnaires assessing overall health, physical activity, sleep, risk behaviors, television viewing, alcohol consumption, and quality of life.

The gastric bypass patients lost weight as expected.

The mean weight of adult family members declined from 220 to 198 pounds, which was not statistically significant. However, when the family members were categorized by their own baseline weight, significant differences emerged.

"Bariatric surgery provides an opportunity for intervention for many individuals beyond the patient."

Obese adult family members showed significant weight loss, from a mean of 234 to 226 pounds. Nonobese adult family members showed a nonsignificant weight loss from 180 to 176 pounds. This pattern held true for decreases in body mass index as well.

The pattern also was the same for waist circumference, with obese adult family members showing a significant decrease from a mean of 119 cm to 111 cm and nonobese adult family members showing no change in waist circumference.

According to these findings, obese adult family members lost 3% of their total weight in 1 year, which falls within the range of a 2%-5% weight loss reported for people following the Atkins, Zone, Ornish, or LEARN diets. "Living with a gastric bypass patient and undertaking a structured diet plan along with the patient may have an equivalent effect on weight," the investigators said (Arch. Surg. 2011;146:1185-90).

Children were analyzed separately because of the expectation that their weight and waist circumference would increase due to natural growth.

Given the growth trajectories documented in their medical charts, obese children actually showed a smaller increase in BMI (29.6) than was expected (31.2). Nonobese children showed a slightly larger increase in BMI (19.8) than was expected (18.8).

As with the adults, children who were obese showed a significant reduction in waist circumference, from 119 cm to 111 cm, but nonobese children did not show any change in waist circumference.

Patients and their adult family members showed significant changes in their eating habits. Both groups had marked decreases in "uncontrolled eating" and in "emotional eating." In addition, patients, but not their relatives, showed significantly increased "cognitive control of eating."

However, children showed no changes in these measures. And neither adult family members nor children changed their food choices or decreased their intake of carbohydrates or junk food, while patients did achieve these goals.

Yet there was a significant increase in the percentage of children who reported that they were "on a diet," from 25% at baseline to 50% at 1 year.

Patients and their adult family members reported significant declines in alcohol consumption, from 5 to 0.2 drinks per month among patients and from 11 to 0.8 drinks per month among adult family members.

Patients, adult relatives, and children all showed significant gains in daily activity levels. Children also decreased the amount of time they spent watching TV or using a computer every day, although this reduction did not reach statistical significance.

Overall, the study findings indicate that "bariatric surgery provides an opportunity for intervention for many individuals beyond the patient," Dr. Woodard and her associates said.

This study was supported by the Medical Scholars Program at Stanford University. No financial conflicts of interest were reported.

Bariatric Surgery Recipients' Family Members Slim Down