When the body is forced into a state of hypercatabolism or hypermetabolism, such as from a wound, burn, sepsis, major surgery, cancer, pulmonary disease, or a major trauma, the patient is at high risk for involuntary weight loss and proteincalorie malnutrition (Table 1). This has serious health implications, with the risk of patient morbidity and mortality increasing in direct proportion to decreases in body weight. The question becomes, then, how much is too much loss of body weight? As suggested by the Omnibus Budget Reconciliation Act (OBRA) of 1987, problematic weight loss includes the following: * severe weight loss: loss of more than 5% body weight in 30 days, more than 7.5% in 60 days, or more than 10% in 180 days. Various formulas can be used to calculate the percentage of body weight lost. One that generally provides a good picture of the patients current state of health is the following: usual weight - actual weight x 100 ./. usual weight = percentage of body weight loss.
One possible health outcome that may be adversely affected by intentional weight loss is immune function. Natural killer (NK) cells, a subset of mononuclear cells, which are an important component of the immune system, lack antigen-specific receptors and are capable of killing cancer cells and virus-infected cells. The aim of a cross-sectional study was to investigate history of intentional weight loss and associations with NK cytotoxicity and lymphocyte subpopulations among healthy, overweight, postmenopausal women. It was hypothesized that repeated intentional weight loss may be associated with lower immune function measures. The subjects (n=114) were a subset of a female study population recruited for an exercise intervention trial. The subjects had to meet the following criteria: postmenopausal, age 50 to 75 years, in good health; sedentary; nonsmoking; and had been at a stable body weight for at least 3 months. Body weight and height was measured. The subjects completed a questionnaire that included the following question: “Within the last 20 years, when you were not pregnant or sick, did you ever lose 10 pounds or more on purpose?” In other questions, women were queried regarding how often they had lost between 120 lb and 19 lb, between 20 lb and 49 lb, 50 lb or more, and how long they had been within 10 lb of their current weight. Demographic information was obtained. Food frequency questionnaires were used to assess dietary intake and alcohol consumption. The use of nutritional supplements was ascertained. Flow cytometry was used to measure NK cytotoxicity at four effector-to-target (E:T) ratios and four enumerating phenotyping lymphocytes. Multiple linear regression was used to investigate associations between weigh loss within the past 20 years and current immune function. Women who reported ever intentionally losing > 10 lbs were found to have lower measured NK cytotoxicity than those who did not (24.7% [+ or -] 12.1% vs. 31.1% [+ or -] 14.7%, respectively, at E:T 25:1; P = .01). Additionally, increasing frequency of previous intentional weight loss was associated with lower NK cytotoxicity (P = .003, trend). As an independent predictor, longer duration of recent weight stability was associated with higher NK cytotoxicity (21.6% [+ or -] 11.9%, 24.4%[+ or -] 11.0%, and 31.9%[+ or -] 14.4% for <2,>2 to <5, and >5 years of weight stability, respectively; P = .0002, trend). The frequency of weight loss episodes was also associated with differences in the number and proportion of NK cells.
Researchers developed an approach that included education about the biological and psychological determinants of body weight, weight loss, and weight regain; cognitive behavioral treatment (CBT) methods to enhance self-esteem and body image (independent of weight); and instruction in behavioral methods of weight control. These investigators report changes in weight, body image, and serf-esteem associated with a novel treatment after 40 weeks of treatment and at a 1-year follow-up (that is, week 92). They also compare these results with those obtained in published trials of standard behavior treatment. Subjects were 17 obese women with a mean age of 46.5 [+ or -] 9.7 years, a mean weight of 92.8 [+ or -] 9.1 kg, and a mean BMI of 34.7 [+ or -] 2.9 kg/[m.sup.2]. Thirteen were white (76.5%), and four were African American (23.5%). The program was designed to alter patients expectations and to promote the acceptance of realistic weight loss outcomes (that is, approximately a 10% weight loss). Subjects were treated in groups of 7 to 10 persons and attended 20 weekly sessions, 5 monthly sessions (over 20 weeks), and a 1-year follow-up visit. The 40-week intervention consisted of four phases. During phase 1 (weeks 1 to 4), the subjects were instructed to refrain from making any changes in their eating or activity habits to focus entirely on examining their weight loss goals and expectations. Phase II of the program (weeks 5 to 12) focused on the development of weight control skills. The subjects were instructed to consume a self-selected diet of 1200 to 1500 kcal/day and were trained in the standard cognitive behavioral methods of weight control. Phase III (weeks 13 to 20) focused on methods to improve body image and self esteem. And finally, phase IV of the program (weeks 24 to 40) focused on developing weight maintenance skills. Weight was measured at each treatment visit. Changes in weight, self-esteem, body image, and quality of life were assessed at the end of treatment and 1 year later. At week 40, participants lost an average of 5.7 [+ or -] 5.3% of initial weight, which was associated with significant improvements in body image, self-esteem, and quality of life. Improvements in psychosocial status were maintained at week 92, although mean weight loss at this time had declined to 2.9 [+ or -] 5.6% of initial weight. Increased satisfaction with body weight at week 40 was associated with significantly better maintenance of weight loss at follow-up (r = -70; p = 0.02).
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