Julie K. Golden

Food cravings and energy regulation: the characteristics of craved foods and their relationship with eating behaviors and weight change during 6 months of dietary energy restriction

Objective:To examine characteristics of craved foods in relation to dietary energy restriction (ER) with high (HG) and low glycemic load (LG) diets.Design:Assessments of food cravings before and during a randomized controlled trial of HG and LG diets provided for 6 months.Subjects:Thirty-two healthy, overweight women aged 20–42 years.Measurements:Self-reported food cravings and dietary intake, body weight, weight history and measures of eating behaviors.Results:Foods craved at baseline were more than twice as high in energy density as the habitual diet (3.7±1.5 vs 1.7±0.3 kcal/g; P<0.001), and on average were lower in protein (P<0.001) and fiber (P<0.001) and higher in fat (P=0.002). There were no statistically significant changes in nutritional characteristics of craved foods after 6 months of ER. There was a significant relationship between reported portion size of craved food consumed at baseline and lifetime high body mass index (r=0.49, P=0.005). Additionally, there was a significant association between susceptibility to hunger and craving frequency at baseline, and there were significant relationships between hunger score, craving frequency, strength and percentage of time that cravings are given in to after 6 months of ER. In multiple regression models, subjects who lost a greater percentage of weight craved higher energy-dense foods at month 6 of ER, but also reported giving in to food cravings less frequently (adjusted R 2=0.31, P=0.009).Conclusion:High energy density and fat content, and low protein and fiber contents were identifying characteristics of craved foods. The relationships between craving variables and hunger score suggest that the relative influence of hunger susceptibility on cravings may be important before and especially after ER. Portion size of craved foods and frequency of giving in to food cravings appear to be important areas for focus in lifestyle modification programs for long-term weight loss.

The Effects of the Dietary Glycemic Load on Type 2 Diabetes Risk Factors during Weight Loss

Objective: To compare the effects of two calorie‐restricted diets that differ in glycemic load (GL) on glucose tolerance and inflammation.

Calorie Restriction Enhances T-Cell–Mediated Immune Response in Adult Overweight Men and Women

Calorie restriction (CR) enhances immune response and prolongs life span in animals. However, information on the applicability of these results to humans is limited. T-cell function declines with age. We examined effects of CR on T-cell function in humans. Forty-six overweight, nonobese participants aged 20-42 years were randomly assigned to 30% or 10% CR group for 6 months. Delayed-type hypersensitivity (DTH), T-cell proliferation (TP), and prostaglandin E(2) (PGE(2)) productions were determined before and after CR. DTH and TP to T-cell mitogens were increased in both groups over baseline (p < or = .019). However, number of positive responses to DTH antigens (p = .016) and TP to anti-CD3 reached statistical significance only after 30% CR (p = .001). Lipopolysaccharide-stimulated PGE(2) was reduced in both groups but reached statistical significance after 30% CR (p < or = .029). These results, for the first time, show that 6-month CR in humans improves T-cell function.

Long-term effects of provided low and high glycemic load low energy diets on mood and cognition.

Energy-restricted low glycemic load diets are being used increasingly for weight loss. However, the long-term effects of such regimens on mood and cognitive performance are not known. We assessed the effects of low glycemic load (LG) and high glycemic load (HG) energy-restricted diets on mood and cognitive performance during 6 months of a randomized controlled trial when all food was provided. Subjects were 42 healthy overweight adults (age 35+/-5 years; BMI 27.8+/-1.6 kg/m(2)) with a mean weight loss of 8.7+/-5.0% that did not differ significantly by diet randomization. Mood was assessed by using the Profile of Mood States (POMS) questionnaire. Cognitive performance was assessed by using computerized tests of simple reaction time, vigilance, learning, short-term memory and attention, and language-based logical reasoning. Worsening mood outcome over time was observed in the HG diet group compared to the LG for the depression subscale of POMS (p=0.009 after including hunger as a covariate). There was no significant change over time in any cognitive performance values. These findings suggest a negative effect of an HG weight loss diet on sub-clinical depression but, in contrast to a previous suggestion, provide no support for differential effects of LG versus HD diets on cognitive performance.

Low or Moderate Dietary Energy Restriction for Long-term Weight Loss: What Works Best?

Theoretical calculations suggest that small daily reductions in energy intake can cumulatively lead to substantial weight loss, but experimental data to support these calculations are lacking. We conducted a 1‐year randomized controlled pilot study of low (10%) or moderate (30%) energy restriction (ER) with diets differing in glycemic load in 38 overweight adults (mean ± s.d., age 35 ± 6 years; BMI 27.6 ± 1.4 kg/m2). Food was provided for 6 months and self‐selected for 6 additional months. Measurements included body weight, resting metabolic rate (RMR), adherence to the ER prescription assessed using 2H218O, satiety, and eating behavior variables. The 10%ER group consumed significantly less energy (by 2H218O) than prescribed over 12 months (18.1 ± 9.8%ER, P = 0.04), while the 30%ER group consumed significantly more (23.1 ± 8.7%ER, P < 0.001). Changes in body weight, satiety, and other variables were not significantly different between groups. However, during self‐selected eating (6–12 months) variability in % weight change was significantly greater in the 10%ER group (P < 0.001) and poorer weight outcome on 10%ER was predicted by higher baseline BMI and greater disinhibition (P < 0.0001; adj R2 = 0.71). Weight loss at 12 months was not significantly different between groups prescribed 10 or 30%ER, supporting the efficacy of low ER recommendations. However, long‐term weight change was more variable on 10%ER and weight change in this group was predicted by body size and eating behavior. These preliminary results indicate beneficial effects of low‐level ER for some but not all individuals in a weight control program, and suggest testable approaches for optimizing dieting success based on individualizing prescribed level of ER.

Long-Term Effects of Energy-Restricted Diets Differing in Glycemic Load on Metabolic Adaptation and Body Composition*

A randomized controlled trial of high glycemic load (HG) and low glycemic load (LG) diets with food provided for 6 months and self-administered for 6 additional months at 30% caloric restriction (CR) was performed in 29 overweight adults (mean+/-SD, age 35+/-5y; BMI 27.5+/-1.5 kg/m(2)). Total energy expenditure (TEE), resting metabolic rate (RMR), fat and fat free mass (FFM), were measured at 3, 6 and 12 months. Changes in TEE, but not changes in RMR, were greater than accounted for by the loss of FFM and fat mass (P=0.001-0.013) suggesting an adaptive response to long-term CR. There was no significant effect of diet group on change in RMR or TEE. However, in subjects who lost >5% body weight (n=26), the LG diet group had a higher percentage of weight loss as fat than the HG group (p<0.05), a finding that may have implications for dietary recommendations during weight reduction.

Use of cereal fiber to facilitate adherence to a human caloric restriction program

Background and aims: Caloric restriction (CR) attenuates biological aging in animal models but there is little information on the feasibility and efficacy of CR regimens in humans. We examined the effects of consuming an insoluble cereal fiber supplement on ability to sustain CR over 1 year in healthy overweight adults. Methods: In 34 healthy overweight women and men (BMI 25–30 kg/m2, age 20–42 yr), a 30% CR regimen meeting national recommendations for dietary fiber was provided for 24 weeks, and for an additional 24 weeks subjects were counseled to prepare the same regimen at home. During 5–10 weeks of CR, subjects were randomized to consume an extra 20 g/day of dietary fiber from a high fiber cereal (+F) or to not consume additional fiber (−F). After this time, all subjects were encouraged to consume the extra fiber. Outcomes included adherence to the provided and self-prepared CR regimens (energy intake determined using doubly labeled water), changes in body weight, and self-reported satisfaction with the amount of consumed food. Results: During 5–10 weeks of CR when all food was provided, both +F and −F groups were highly adherent to the CR regimen and there was no significant difference between groups in energy intake (p=0.51), weight change (p=0.96), or satisfaction with amount of provided food (p=0.08). During self-prepared CR from 25 to 48 weeks, mean adherence was lower than during the food-provided phase and there was a significant association between fiber intake and % CR (r=0.69, p<0.001), decreased BMI (r=− 0.38, p=0.04) and satisfaction with the amount of consumed food (r=0.59, p=0.002). Conclusions: A high fiber cereal intake may facilitate CR in humans self-selecting their own food; longer-term intervention studies are needed to confirm these findings.