Hormonal responses to a fast-food meal compared with nutritionally comparable meals of different composition.

BACKGROUND: Fast food is consumed in large quantities each day. Whether there are differences in the acute metabolic response to these meals as compared to 'healthy' meals with similar composition is unknown. DESIGN: Three-way crossover. METHODS: Six overweight men were given a standard breakfast at 8:00 a.m. on each of 3 occasions, followed by 1 of 3 lunches at noon. The 3 lunches included: (1) a fast-food meal consisting of a burger, French fries and root beer sweetened with high fructose corn syrup; (2) an organic beef meal prepared with organic foods and a root beer containing sucrose, and (3) a turkey meal consisting of a turkey sandwich and granola made with organic foods and an organic orange juice. Glucose, insulin, free fatty acids, ghrelin, leptin, triglycerides, LDL-cholesterol and HDL-cholesterol were measured at 30-min intervals over 6 h. Salivary cortisol was measured after lunch. RESULTS: Total fat, protein and energy content were similar in the 3 meals, but the fatty acid content differed. The fast-food meal had more myristic (C14:0), palmitic (C16:0), stearic (C18:0) and trans fatty acids (C18:1) than the other 2 meals. The pattern of nutrient and hormonal response was similar for a given subject to each of the 3 meals. The only statistically significant acute difference observed was a decrease in the AUC of LDL cholesterol after the organic beef meal relative to that for the other two meals. Other metabolic responses were not different. CONCLUSION: LDL-cholesterol decreased more with the organic beef meal which had lesser amounts of saturated and trans fatty acids than in the fast-food beef meal.

AgRP-deficiency could lead to increased lifespan.

The Agouti-related protein (AgRP) is a central orexigenic peptide leading to increased food intake when ubiquitously overexpressed. AgRP-deficient (AgRP(-/-)) mice have either no phenotype or present an age-related leanness. In this study, AgRP(-/-) mice were fed alternate high fat or low fat diets in an effort to determine whether AgRP is a mediating factor for the effects of dietary fat on metabolic parameters. There were no striking metabolic differences between AgRP(-/-) and the equally obese wild type littermates but AgRP(-/-) mice displayed a significantly longer lifespan. The point estimate of median survival for the AgRP(-/-) group was 9.8% greater while the significantly low hazard ratio (0.494) suggests that mortality incidence of AgRP(-/-) mice is less than one-half that of the wild type reference population. It is concluded that although AgRP(-/-) mice become morbidly obese consuming a high fat diet (a landmark feature for a shortened lifespan), they seem to overcome obesity- and age-related pathologies and live significantly longer than their metabolically similar wild type littermates.

A primary care weight management intervention for low-income African-American women.

OBJECTIVE: To determine whether a tailored weight management program, addressing the needs of obese, low-income African-American women, would produce greater weight loss than standard medical care. RESEARCH METHODS AND PROCEDURES: A randomized, controlled trial was conducted between 1999 and 2003 with 144 overweight or obese women (predominantly African-American) enrolled at two primary care clinics. Four physicians at each clinic were randomly assigned to provide either tailored weight management interventions or standard care. The tailored condition consisted of six monthly outpatient visits lasting approximately 15 minutes each, which included personalized materials and messages. The main outcome was body weight change. RESULTS: The intervention group lost more weight than the standard care group (p = 0.03). The tailored group lost a mean (standard deviation) of 2.0 (3.2) kg by Month 6. The standard care group gained 0.2 (2.9) kg. More participants in the tailored group lost weight (79% vs. 47%; p = 0.04). DISCUSSION: Obese, low-income, African-American women provided with 90 minutes of physician-delivered, tailored weight management instruction over 6 months achieved greater weight loss than those receiving standard medical care. The primary care physician can be effective in delivering weight loss interventions, and the primary care clinic may be a useful setting to implement weight management interventions.

Consistency of food intake over four eating sessions in the laboratory.

OBJECTIVE: The aim of this study was to test the consistency (repeatability) of laboratory measures of food intake, including eating microstructure (cumulative food intake curves), in non-obese humans across four eating sessions, each separated by 1 week. A secondary aim was to test the effect of dietary restraint on the food intake of female participants. METHODS: Mixed model analyses were used to compare average food intake across sessions, and intraclass correlation coefficients (ICC) were employed to compare within subject variability to total variance. High and low restraint females and low restraint males consumed four lunches in a Universal Eating Monitor (UEM) laboratory. The lunches consisted of one type of sandwich (chicken salad sandwich squares) or three types of sandwiches (chicken salad, ham, and turkey sandwich squares) presented in counterbalanced order. RESULTS: Measures of food intake were stable for men and women, regardless of sandwich variety. In females, level of dietary restraint (high vs. low) did not significantly affect food intake. DISCUSSION: The results indicate that eating behavior in the laboratory is sufficiently stable over time to justify evaluation of interventions designed to alter food intake using within subject designs.

Reproducibility of endurance performance on a treadmill using a preloaded time trial.

PURPOSE: The purpose of this study was to establish a highly reproducible test to measure endurance performance in runners. METHODS: We evaluated the reproducibility of endurance performance during a 10-km time trial performed on a treadmill after a 90-min preload run at 65% of maximal oxygen uptake VO2max). After screening and a practice test, eight endurance runners (4 men, 4 women, 33.4 +/- 10.1 yr, VO2max = 60.3 +/- 6.3 mL x kg(-1) x min(-1) in men and 51.8 +/- 2.2 mL x kg(-1) x min(-1) in women, mean +/- SD) completed two preloaded time trial tests spaced 3-4 wk apart in men and one menstrual cycle apart in women. A high-carbohydrate diet (15% protein, 10% fat, 75% carbohydrate) was provided the day before both tests. RESULTS: Runners completed time trial 1 and time trial 2 in 45:41 +/- 4:45 and 45:24 +/- 5:03 min:s, respectively (43:29 +/- 5:02 and 43:12 +/- 5:14 min:s for men and 47:53 +/- 3:47 and 47:35 +/- 4:23 min:s for women, trials 1 and 2, respectively). The within-subject coefficient of variation for 10-km time was 1.00% +/- 0.25% (point estimate +/- estimated standard error) (0.54% +/- 0.19% for men and 1.26% +/- 0.45% for women). CONCLUSION: These results suggest that performance measured as time to complete a 10-km time trial on a treadmill after a 90-min preload is extremely reliable and may be useful for future research assessing the effect of diet, ergogenic substances, or training methods on endurance running performance.

Weight loss in rats exposed to repeated acute restraint stress is independent of energy or leptin status.

Acute release of corticotropin-releasing factor (CRF) during repeated restraint (3-h restraint on each of 3 days) causes temporary hypophagia but chronic suppression of body weight in rats. Here we demonstrated that a second bout of repeated restraint caused additional weight loss, but continuing restraint daily for 10 days did not increase weight loss because the rats adapted to the stress. In these two studies serum leptin, which suppresses the endocrine response to stress, was reduced in restrained rats. Peripheral infusion of leptin before and during restraint did not prevent stress-induced weight loss, although stress-induced corticosterone release was suppressed. Restrained rats were hyperthermic during restraint, but there was no evidence that fever or elevated free interleukin-6 caused the sustained reduction in weight. Restraining food-restricted rats caused a small but significant weight loss. Food-restricted rats fed ad libitum after the end of restraint showed a blunted hyperphagia and slower rate of weight regain than their controls. These results indicate that repeated acute stress induces a chronic change in weight independent of stress-induced hypophagia and may represent a change in homeostasis initiated by repeated acute activation of the central CRF system.