Donald A. Williamson

Comparison of Weight-Loss Diets with Different Compositions of Fat, Protein, and Carbohydrates

BACKGROUND The possible advantage for weight loss of a diet that emphasizes protein, fat, or carbohydrates has not been established, and there are few studies that extend beyond 1 year. METHODS We randomly assigned 811 overweight adults to one of four diets; the targeted percentages of energy derived from fat, protein, and carbohydrates in the four diets were 20, 15, and 65%; 20, 25, and 55%; 40, 15, and 45%; and 40, 25, and 35%. The diets consisted of similar foods and met guidelines for cardiovascular health. The participants were offered group and individual instructional sessions for 2 years. The primary outcome was the change in body weight after 2 years in two-by-two factorial comparisons of low fat versus high fat and average protein versus high protein and in the comparison of highest and lowest carbohydrate content. RESULTS At 6 months, participants assigned to each diet had lost an average of 6 kg, which represented 7% of their initial weight; they began to regain weight after 12 months. By 2 years, weight loss remained similar in those who were assigned to a diet with 15% protein and those assigned to a diet with 25% protein (3.0 and 3.6 kg, respectively); in those assigned to a diet with 20% fat and those assigned to a diet with 40% fat (3.3 kg for both groups); and in those assigned to a diet with 65% carbohydrates and those assigned to a diet with 35% carbohydrates (2.9 and 3.4 kg, respectively) (P>0.20 for all comparisons). Among the 80% of participants who completed the trial, the average weight loss was 4 kg; 14 to 15% of the participants had a reduction of at least 10% of their initial body weight. Satiety, hunger, satisfaction with the diet, and attendance at group sessions were similar for all diets; attendance was strongly associated with weight loss (0.2 kg per session attended). The diets improved lipid-related risk factors and fasting insulin levels. CONCLUSIONS Reduced-calorie diets result in clinically meaningful weight loss regardless of which macronutrients they emphasize. (ClinicalTrials.gov number, NCT00072995.)

Long-term effects of a lifestyle intervention on weight and cardiovascular risk factors in individuals with type 2 diabetes mellitus: Four-year results of the look AHEAD trial

BACKGROUND Lifestyle interventions produce short-term improvements in glycemia and cardiovascular disease (CVD) risk factors in individuals with type 2 diabetes mellitus, but no long-term data are available. We examined the effects of lifestyle intervention on changes in weight, fitness, and CVD risk factors during a 4-year study. METHODS The Look AHEAD (Action for Health in Diabetes) trial is a multicenter randomized clinical trial comparing the effects of an intensive lifestyle intervention (ILI) and diabetes support and education (DSE; the control group) on the incidence of major CVD events in 5145 overweight or obese individuals (59.5% female; mean age, 58.7 years) with type 2 diabetes mellitus. More than 93% of participants provided outcomes data at each annual assessment. RESULTS Averaged across 4 years, ILI participants had a greater percentage of weight loss than DSE participants (-6.15% vs -0.88%; P < .001) and greater improvements in treadmill fitness (12.74% vs 1.96%; P < .001), hemoglobin A(1c) level (-0.36% vs -0.09%; P < .001), systolic (-5.33 vs -2.97 mm Hg; P < .001) and diastolic (-2.92 vs -2.48 mm Hg; P = .01) blood pressure, and levels of high-density lipoprotein cholesterol (3.67 vs 1.97 mg/dL; P < .001) and triglycerides (-25.56 vs -19.75 mg/dL; P < .001). Reductions in low-density lipoprotein cholesterol levels were greater in DSE than ILI participants (-11.27 vs -12.84 mg/dL; P = .009) owing to greater use of medications to lower lipid levels in the DSE group. At 4 years, ILI participants maintained greater improvements than DSE participants in weight, fitness, hemoglobin A(1c) levels, systolic blood pressure, and high-density lipoprotein cholesterol levels. CONCLUSIONS Intensive lifestyle intervention can produce sustained weight loss and improvements in fitness, glycemic control, and CVD risk factors in individuals with type 2 diabetes. Whether these differences in risk factors translate to reduction in CVD events will ultimately be addressed by the Look AHEAD trial. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT00017953.

The Look AHEAD study: a description of the lifestyle intervention and the evidence supporting it.

The Look AHEAD (Action for Health in Diabetes) study is a multicenter, randomized controlled trial designed to determine whether intentional weight loss reduces cardiovascular morbidity and mortality in overweight individuals with type 2 diabetes. The study began in 2001 and is scheduled to conclude in 2012. A total of 5145 participants have been randomly assigned to a lifestyle intervention or to an enhanced usual care condition (i.e., diabetes support and education). This article describes the lifestyle intervention and the empirical evidence to support it. The two principal intervention goals are to induce a mean loss ≥ 7% of initial weight and to increase participants’ moderately intense physical activity to ≥175 min/wk. For the first 6 months, participants attend one individual and three group sessions per month and are encouraged to replace two meals and one snack a day with liquid shakes and meal bars. From months 7 to 12, they attend one individual and two group meetings per month and continue to replace one meal per day (which is recommended for the studys duration). Starting at month 7, more intensive behavioral interventions and weight loss medication are available from a toolbox, designed to help participants with limited weight loss. In Years 2 to 4, treatment is provided mainly on an individual basis and includes at least one on‐site visit per month and a second contact by telephone, mail, or e‐mail. After Year 4, participants are offered monthly individual visits. The intervention is delivered by a multidisciplinary team that includes medical staff who monitor participants at risk of hypoglycemic episodes.

Metabolic and Behavioral Compensations in Response to Caloric Restriction: Implications for the Maintenance of Weight Loss

Background Metabolic and behavioral adaptations to caloric restriction (CR) in free-living conditions have not yet been objectively measured. Methodology and Principal Findings Forty-eight (36.8±1.0 y), overweight (BMI 27.8±0.7 kg/m2) participants were randomized to four groups for 6-months; Control: energy intake at 100% of energy requirements; CR: 25% calorie restriction; CR+EX: 12.5% CR plus 12.5% increase in energy expenditure by structured exercise; LCD: low calorie diet (890 kcal/d) until 15% weight reduction followed by weight maintenance. Body composition (DXA) and total daily energy expenditure (TDEE) over 14-days by doubly labeled water (DLW) and activity related energy activity (AREE) were measured after 3 (M3) and 6 (M6) months of intervention. Weight changes at M6 were −1.0±1.1% (Control), −10.4±0.9% (CR), −10.0±0.8% (CR+EX) and −13.9±0.8% (LCD). At M3, absolute TDEE was significantly reduced in CR (−454±76 kcal/d) and LCD (−633±66 kcal/d) but not in CR+EX or controls. At M6 the reduction in TDEE remained lower than baseline in CR (−316±118 kcal/d) and LCD (−389±124 kcal/d) but reached significance only when CR and LCD were combined (−351±83 kcal/d). In response to caloric restriction (CR/LCD combined), TDEE adjusted for body composition, was significantly lower by −431±51 and −240±83 kcal/d at M3 and M6, respectively, indicating a metabolic adaptation. Likewise, physical activity (TDEE adjusted for sleeping metabolic rate) was significantly reduced from baseline at both time points. For control and CR+EX, adjusted TDEE (body composition or sleeping metabolic rate) was not changed at either M3 or M6. Conclusions For the first time we show that in free-living conditions, CR results in a metabolic adaptation and a behavioral adaptation with decreased physical activity levels. These data also suggest potential mechanisms by which CR causes large inter-individual variability in the rates of weight loss and how exercise may influence weight loss and weight loss maintenance. Trial Registration ClinicalTrials.gov NCT00099151

Evidence for attention to threatening stimuli in depression

A modified version of the attentional deployment task developed by MacLeod, Mathews and Tata (1986) [Journal of Abnormal Psychology, 95, 15-20] was used to examine two issues: first, whether there was any evidence of attentional bias in depressed subjects, rather than in anxious subjects alone; and second, whether attentional effects would occur in the location of stimuli that could not be identified. Subjects were presented with pairs of words, one above the other, and the extent to which attention favored threatening rather than neutral words was assessed from the latency to detect a dot in the same location of one them. These detection latencies showed that depressed, but not anxious subjects, were selectively attentive to socially threatening words. There was also evidence for attentional effects in the anxious subjects favoring physically threatening words. Furthermore, panic disorder patients were preferentially attentive to the location of physically-threatening stimuli that could not be accurately identified. Overall, the results provide further evidence that emotionally disturbed subjects tend to orient attention towards personally-relevant emotional stimuli. However, the previous hypothesis that this attentional bias occurs only in anxiety, and not in depression, was not supported.

Effects of stevia, aspartame, and sucrose on food intake, satiety, and postprandial glucose and insulin levels.

UNLABELLED Consumption of sugar-sweetened beverages may be one of the dietary causes of metabolic disorders, such as obesity. Therefore, substituting sugar with low calorie sweeteners may be an efficacious weight management strategy. We tested the effect of preloads containing stevia, aspartame, or sucrose on food intake, satiety, and postprandial glucose and insulin levels. DESIGN 19 healthy lean (BMI=20.0-24.9) and 12 obese (BMI=30.0-39.9) individuals 18-50 years old completed three separate food test days during which they received preloads containing stevia (290kcal), aspartame (290kcal), or sucrose (493kcal) before the lunch and dinner meal. The preload order was balanced, and food intake (kcal) was directly calculated. Hunger and satiety levels were reported before and after meals, and every hour throughout the afternoon. Participants provided blood samples immediately before and 20min after the lunch preload. Despite the caloric difference in preloads (290kcal vs. 493kcal), participants did not compensate by eating more at their lunch and dinner meals when they consumed stevia and aspartame versus sucrose in preloads (mean differences in food intake over entire day between sucrose and stevia=301kcal, p<.01; aspartame=330kcal, p<.01). Self-reported hunger and satiety levels did not differ by condition. Stevia preloads significantly reduced postprandial glucose levels compared to sucrose preloads (p<.01), and postprandial insulin levels compared to both aspartame and sucrose preloads (p<.05). When consuming stevia and aspartame preloads, participants did not compensate by eating more at either their lunch or dinner meal and reported similar levels of satiety compared to when they consumed the higher calorie sucrose preload.

Impact of a Weight Management Program on Health-related Quality of Life In Overweight Adults with Type 2 Diabetes

BACKGROUND Inconsistent findings have been reported regarding improved health-related quality of life (HRQOL) after weight loss. We tested the efficacy of a weight management program for improving HRQOL in overweight or obese adults diagnosed as having type 2 diabetes mellitus. METHODS We conducted a randomized multisite clinical trial at 16 outpatient research centers with 2 treatment arms and blinded measurements at baseline and the end of year 1. A total of 5145 participants (mean [SD] age, 58.7 [6.9] years; mean [SD] body mass index [calculated as weight in kilograms divided by height in meters squared], 36.0 [5.9]; 59.5% women; 63.1% white) were randomized to an intensive lifestyle intervention (ILI) or to diabetes support and education (DSE). Main outcome measures included the 36-Item Short-Form Health Survey physical component summary (PCS) and mental health component summary (MCS) scores and Beck Depression Inventory II (BDI-II) scores. Baseline mean (SD) scores were 47.9 (7.9) for PCS, 54.0 (8.1) for MCS, and 5.7 (5.0) for BDI-II. RESULTS Improved HRQOL was demonstrated by the PCS and BDI-II scores (P < .001) in the ILI arm compared with the DSE arm. The largest effect was observed for the PCS score (difference, -2.91; 99% confidence interval, -3.44 to -2.37). The greatest HRQOL improvement occurred in participants with the lowest baseline HRQOL levels. Mean (SD) changes in weight (ILI, -8.77 [8.2] kg and DSE, -0.86 [5.0] kg), improved fitness, and improved physical symptoms mediated treatment effects associated with the BDI-II and PCS. CONCLUSIONS Overweight adults diagnosed as having type 2 diabetes experienced significant improvement in HRQOL by enrolling in a weight management program that yielded significant weight loss, improved physical fitness, and reduced physical symptoms. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT00017953.

Mood-congruent memory in depression: Emotional priming or elaboration?

We investigated whether mood-congruent memory (MCM) bias in depression is a function of implicit or explicit memory. Implicit memory is taken as a measure of ease of activation, whereas explicit memory also taps elaboration. As expected, MCM bias was found in the explicit memory task but not in the implicit memory task. We believe this finding supports the involvement of elaborative mechanisms in MCM. In addition, memory bias was found with words related to depression but not with words denoting physical threat. Thus, the MCM bias in explicit memory was found to be specific to information that was congruent with depression rather than to all negative information.

Cognitive Bias in Eating Disorders:: Implications for Theory and Treatment

Research testing the predictions of cognitive-behavioral theory related to the psychopathology of eating disorders has lagged behind treatment outcome research. Central to cognitive theories of eating disorders is the hypothesis that beliefs and expectancies pertaining to body size and to eating are biased in favor of selectively processing information related to fatness/thinness, dieting, and control of food intake or body weight. In recent years, controlled investigations of the predictions of cognitive theories of eating disorders have yielded empirical support for these theories. This paper reviews research which has tested the predictions of cognitive-behavioral theory and discusses the implications of these findings for the treatment of eating disorders. Understanding of information processing biases may assist the clinician in understanding a range of psychopathological features of anorexia and bulimia nervosa, including denial, resistance to treatment, and misinterpretation of therapeutic interventions.

Cognitive-Behavioral Theories of Eating Disorders:

This article presents an integrated cognitive-behavioral theory of eating disorders that is based on hypotheses developed over the past 30 years. The theory is evaluated using a selected review of the eating disorder literature pertaining to cognitive biases, negative emotional reactions, binge eating, compensatory behaviors, and risk factors for eating disorders. In general, hypotheses derived from cognitive-behavioral theories have been supported by a variety of research studies. The implications of these findings for treatment and prevention of eating disorders are discussed. This review of the literature serves as a conceptual base for some of the other articles that are included in this special issue of Behavior Modification. The article concludes with an introduction to six articles that discuss issues related to psychiatric classification, assessment, treatment, and prevention of eating disorders.