Physiology of fat replacement and fat reduction: effects of dietary fat and fat substitutes on energy regulation

Spices and energy balance

The sensory properties of foods and beverages are primary determinants of food choice. Some flavor components have an inherent hedonic valence that influences ingestive behavior. However, these hedonic impressions may be modified and others newly formed through their association with the post-ingestive consequences of food and beverage consumption. Flavor-active compounds, including spices, also modify digestive, absorptive and metabolic processes through direct activation of signaling pathways or via neurally-mediated cephalic phase responses. These may modify energy balance through effects on food digestion, energy absorption and metabolism. Thus, collectively, flavor has the potential to modify energy balance. Attempts to purposefully augment energy and nutrient intake have largely focused on the aging population where flavor fortification is posited to correct for diminishing sensory function. Evidence of efficacy is not strong, possibly due to methodological issues such as low statistical power and failure to match documented sensory limitations with the nature of the intervention. More rigorous testing should determine the viability of this therapeutic application of food flavors. The use of flavor compounds for weight reduction has yielded mixed results. Most trials have delivered the compounds via capsule precluding assessment of flavor to outcomes. Work with red pepper suggests there is an independent, albeit subtle, sensory effect on substrate oxidation coupled with a more general reduction of appetite and enhancement of energy expenditure. Flavor active compounds hold some promise for being more a part of the solution than the problem of disordered eating and unhealthy weight.

Maternal manganese restriction increases susceptibility to high-fat diet-induced dyslipidemia and altered adipose function in WNIN male rat offspring

Growth in utero is largely a reflection of nutrient and oxygen supply to the foetus. We studied the effects of Mn restriction per se, maternal Mn restriction, and postnatal high-fat feeding in modulating body composition, lipid metabolism and adipocyte function in Wistar/NIN (WNIN) rat offspring. Female weanling, WNIN rats received ad libitum for 4 months, a control or Mn-restricted diet and were mated with control males. Some restricted mothers were rehabilitated with control diet from conception (MnRC) or parturition (MnRP), and their offspring were raised on control diet. Some restricted offspring were weaned onto control diet (MnRW), while others continued on restricted diet throughout (MnR). A set of offspring from each group was fed high-fat diet from 9 months onwards. Body composition, adipocytes function, and lipid metabolism were monitored in male rat offspring at regular intervals. Maternal manganese restriction increased the susceptibility of the offspring to high-fat-induced adiposity, dyslipidaemia, and a proinflammatory state but did not affect their glycemic or insulin status.

Consumption of a high-fat diet induces central insulin resistance independent of adiposity

Plasma insulin enters the CNS where it interacts with insulin receptors in areas that are related to energy homeostasis and elicits a decrease of food intake and body weight. Here, we demonstrate that consumption of a high-fat (HF) diet impairs the central actions of insulin. Male Long-Evans rats were given chronic (70-day) or acute (3-day) ad libitum access to HF, low-fat (LF), or chow diets. Insulin administered into the 3rd-cerebral ventricle (i3vt) decreased food intake and body weight of LF and chow rats but had no effect on HF rats in either the chronic or the acute experiment. Rats chronically pair-fed the HF diet to match the caloric intake of LF rats, and with body weights and adiposity levels comparable to those of LF rats, were also unresponsive to i3vt insulin when returned to ad libitum food whereas rats pair-fed the LF diet had reduced food intake and body weight when administered i3vt insulin. Insulin's inability to reduce food intake in the presence of the high-fat diet was associated with a reduced ability of insulin to activate its signaling cascade, as measured by pAKT. Finally, i3vt administration of insulin increased hypothalamic expression of POMC mRNA in the LF- but not the HF-fed rats. We conclude that consumption of a HF diet leads to central insulin resistance following short exposure to the diet, and as demonstrated by reductions in insulin signaling and insulin-induced hypothalamic expression of POMC mRNA.

The effect of high-fat diet-induced obesity on cardiovascular toxicity in Wistar albino rats

The consumption of a high-fat diet (HFD) is considered a risk factor for obesity development. Nonetheless, a causal role of dietary fat has never been documented, because of inadequate animal models. In our study, one group of rats was fed with standard rat diet, while other group of rats fed with high-fat diet for 4 weeks. After 4 weeks of feeding, the hemodynamic parameters in the rats fed with HFD were significantly increased as compared with control rats. Rats fed with HFD had elevated levels of serum lipids, insulin, leptin, glucose and apolipoprotein B. Lipid peroxides and caspase-3 levels were increased while serum apolipoprotein A1 and antioxidant enzymes levels in heart tissues were decreased in HFD-induced obesity in rats as compared to normal healthy control rats fed on standard rat pellet diet. This model of diet-induced obesity will be a useful tool for studying the mechanisms by which dietary fat induces the obesity in humans.

Effect of fat replacement by inulin or lupin-kernel fibre on sausage patty acceptability, post-meal perceptions of satiety and food intake in men

The present study examined whether replacing fat with inulin or lupin-kernel fibre influenced palatability, perceptions of satiety, and food intake in thirty-three healthy men (mean age 52 years, BMI 27·4kg/m2), using a within-subject design. On separate occasions, after fasting overnight, the participants consumed a breakfast consisting primarily of either a full-fat sausage patty (FFP) or a reduced-fat patty containing inulin (INP) or lupin-kernel fibre (LKP). Breakfast variants were alike in mass, protein and carbohydrate content; however the INP and LKP breakfasts were 36 and 37% lower in fat and 15 and 17% lower in energy density respectively compared with the FFP breakfast. The participants rated their satiety before breakfast then evaluated patty acceptability. Satiety was rated immediately after consuming the breakfast, then over the subsequent 4·5h whilst fasting. Food consumed until the end of the following day was recorded. All patties were rated above ‘neither acceptable or unacceptable’, however the INP rated lower for general acceptability (P=0·039) and the LKP lower for flavour (P=0·023) than the FFP. The LKP breakfast rated more satiating than the INP (P=0·010) and FFP (P=0·016) breakfasts. Total fat intake was 18g lower on the day of the INP (P=0·035) and 26g lower on the day of the LKP breakfast (P=0·013) than the FFP breakfast day. Energy intake was lower (1521kJ) only on the day of the INP breakfast (P=0·039). Both inulin and lupin-kernel fibre appear to have potential as fat replacers in meat products and for reducing fat and energy intake in men.

Eating patterns and dietary composition in relation to BMI in younger and older adults

OBJECTIVE

To compare relative associations of eating patterns and dietary composition with body mass index (BMI) in younger (aged 20-59 years, n=1792) and older (aged 60-90 years, n=893) participants in the Continuing Survey of Food Intakes by Individuals, collected 1994-1996.

METHODS

Data from two 24-h dietary recalls from individuals reporting physiologically plausible energy intake (within +/-22% of predicted energy requirements, based on previously published methods) were used.

RESULTS

Mean reported energy intake was 96 and 95% of predicted energy requirements in younger and older subjects, respectively. Older subjects were less likely than younger subjects to skip a meal, but snacking was common in both age groups. Fiber density was significantly higher in the older group. A higher BMI in both age groups was associated with a higher total daily energy intake, and higher energy intakes at all eating occasions. In both age groups, eating frequency was positively associated with energy intake, and eating more than three times a day was associated with being overweight or obese. In the younger group but not the older group, a lower fiber density coupled with higher percentage of energy from fat was independently associated with having a higher BMI.

CONCLUSIONS

While no one eating occasion contributes more than any other to excess adiposity, eating more often than three times a day may play a role in overweight and obesity in both younger and older persons. A reduced satiety response to dietary fiber in addition to lower energy expenditure may potentially further contribute to weight gain in older persons.

The effect of grape-seed extract on 24 h energy intake in humans

OBJECTIVE

Since grape-seed extract has been shown to stimulate lipolysis in vitro and reduce food intake in rats, we assessed the efficacy of grape-seed extract with respect to energy intake (EI) and satiety.

DESIGN

In a randomized, placebo-controlled, double-blind, cross-over study, 51 subjects (age 18-65 y, body mass index 22-30 kg/m2) ate an ad libitum lunch and dinner twice in the University Restaurant for 3 days. Standard breakfasts and snacks were provided. Supplements were taken 30-60 min prior to each meal.

RESULTS

In the total study population, no difference in 24 h EI was found between the grape-seed extract and placebo. However, in the subgroup of subjects (n=23) with an energy requirement > or =the median of 7.5 MJ/day, EI was reduced by 4% (DeltaEI 352.1 kJ/24 h, P=0.05) after grape-seed extract compared to placebo treatment. Meanwhile, there were no significant differences in macronutrient composition, attitude towards eating, satiety, mood or tolerance.

CONCLUSIONS

Grape seed reduced 24 h EI, with on average 4% in subjects who had an energy requirement > or =7.5 MJ/day, without further effects on satiety, mood or tolerance. These findings suggest that grape seed could be effective in reducing 24 h EI in normal to overweight dietary unrestrained subjects, and could, therefore, play a significant role in body-weight management.

Food consumed does not account for the higher prevalence of obesity among stunted adults in a very-low-income population in the Northeast of Brazil (Maceió, Alagoas)

OBJECTIVE

To study the food pattern of stunted and nonstunted, obese and nonobese individuals in a very-low-income population.

DESIGN

A household survey.

SETTING

Slum set up by the 'Homeless Movement', city of Maceió (Alagoas), Brazil.

SUBJECTS AND METHODS

A total of 532 adults classified by sex, stature (Z</= and Z > -2s.d. of the NCHS curves), and body mass index (BMI) were compared using the following variables: waist circumference, waist-hip circumference ratio (W/H), percentage body fat (skinfold thickness and bioelectrical impedance), and food intake (24-h recall).

RESULTS

The prevalence of stunting was 22.6%. In all, 30% of the stunted subjects were overweight or obese, compared with 23% for the nonstunted individuals (P<0.05). In women, logistic regression analysis showed a strong association among weight, abdominal fat, and stunting (r=0.81). No significant differences were observed in the values of W/H or in the qualitative menu of the different categories. Energy intake was below the RDA figures (about 63%). There was similarity among the groups regarding the proportion of macronutrients, except for the fact that stunted obese women ingested less fat and protein than nonstunted obese women. Stunted obese individuals consumed less energy (5962 kJ) than the population as a whole (6213 kJ), an amount far lower than their average needs, which were calculated on the basis of their shorter stature (8109 kJ).

CONCLUSION

The observed energy consumption seems compatible with the panorama of undernutrition present in the population, but it does not explain the high prevalence of obesity detected.

A controlled high-fat diet induces an obese syndrome in rats

The prevalence of obesity is increasing. Although the etiology of obesity is complex, dietary factors, particularly the consumption of a high-fat (HF) diet, is considered a risk factor for its development. Nonetheless, a causal role of dietary fat has never been definitively documented, in part because of inadequate animal models. We developed a rat model of diet-induced obesity that will be a powerful tool for assessment of this issue. In four experiments, Long-Evans rats ate ad libitum a synthetic semipurified diet containing 20 g (HF) or 4 g [low-fat (LF)] of fat/100 g of diet or a nonpurified diet. Other rats ate ad libitum the HF diet in amounts matched to the energy intake of the LF rats. When compared over 10 wk of free feeding, HF rats weighed 10% more (P < 0.01) than LF rats and had 50% more body fat (P < 0.01), as well as significant hyperleptinemia and insulin resistance. Compared with rats fed the nonpurified diet, the HF rats had even more marked differences in these variables. The rats fed the HF diet to match the rats fed the LF diet had similar body weights but significantly more adipose tissue than LF rats, suggesting that diet composition and/or energy density of the diet affects fat deposition. This dietary regimen has reproducible effects on body size and composition, and these are similar in male and female rats. This model of diet-induced obesity will be a useful tool for studying the mechanisms by which dietary fat influences the regulation of energy balance.

Procedures for screening out inaccurate reports of dietary energy intake

OBJECTIVE

To review existing methods and illustrate the use of a new, simple method for identifying inaccurate reports of dietary energy intake (rEI).

DESIGN

Comparison of rEI with energy requirements estimated by using total energy expenditure predicted (pTEE) from age, weight, height and sex using a previously published equation. Propagation of error calculations was performed and cut-offs for excluding rEI at plus or minus two standard deviations (+/-2 SD) and +/-1 SD for the agreement between rEI and pTEE were established.

SETTING

Dietary survey in a US national cohort: the Continuing Survey of Food Intakes by Individuals (CSFII), 1994-96.

SUBJECTS

Men and non-pregnant, non-lactating women aged 21-45 years in the CSFII who provided two multiple-pass 24-hour recalls, height and weight (n = 3755).

RESULTS

Average rEI was 77% of pTEE in men, and 64% of pTEE in women. Calculated cut-offs were rEI <40% or >160% of pTEE (+/-2 SD) and <70% or >130% of pTEE (+/-1 SD), respectively. Use of only the +/-1 SD cut-offs, not the +/-2 SD cut-offs, resulted in a relationship between rEI and body weight similar to what was expected (based on an independently calculated relationship between rEI and measured TEE). Exclusion of rEI outside either the +/-2 SD (11% of subjects) or +/-1 SD (57% of subjects) cut-offs did not affect mean reported macronutrient intakes, but did markedly affect relationships between dietary composition and body mass index.

CONCLUSIONS

When examining relationships between diet and health, use of +/-1 SD cut-offs may be preferable to +/-2 SD cut-offs for excluding inaccurate dietary reports.

Role of food prepared away from home in the American diet, 1977-78 versus 1994-96: changes and consequences

OBJECTIVE

To examine changes, between 1977-78 and 1994-96, in the quantity and quality of food Americans consumed that was prepared at home versus away from home.

DESIGN

Data were obtained from nationwide surveys of food consumption conducted by the US Department of Agriculture (USDA) in 1977-78 and 1994-96. To maximize comparability, we used "day 1" dietary data, which both surveys collected via 24-hour recall.

SUBJECTS/SETTINGS

Individuals 2 years of age and over were selected. USDA sampling weights were used to generate nationally representative estimates.

VARIABLES MEASURED

We categorized foods by preparation at home or at restaurants, fast-food establishments, schools/day care, and other non-home locations. We assessed percent calories from total fat and saturated fat, and the cholesterol, sodium, fiber, calcium, and iron densities of foods prepared at home versus those prepared away from home.

STATISTICAL ANALYSES

T tests were calculated using accepted procedures to adjust for survey design effects.

RESULTS

Between 1977-78 and 1994-96, consumption of food prepared away from home increased from 18% to 32% of total calories. Meals and snacks based on food prepared away from home contained more calories per eating occasion, and "away" food was higher in total fat and saturated fat on a per-calorie basis than at-home food. "Away" food contained less dietary fiber, calcium, and iron on a per-calorie basis. Among adults but not children, food prepared away from home was more sodium and cholesterol dense.

IMPLICATIONS

When developing intervention messages and strategies, nutrition educators need to be aware of the increasing role of "away" food in Americans' diets.

Eating behavior correlates of adult weight gain and obesity in healthy women aged 55-65 y

BACKGROUND

The specific underlying causes of adult weight gain remain uncertain.

OBJECTIVE

The objective was to determine the association of 3 measures of eating behavior with weight gain and body mass index (BMI; in kg/m(2)) in adults.

DESIGN

Current dietary restraint, disinhibition, and hunger were assessed with the use of the Eating Inventory in 638 healthy, nonsmoking women aged 55-65 y. In addition, subjects reported their current weight and height, their weight for 6 age intervals, and changes in voluntary dietary energy restriction over the past 10 y. Current weight and height were validated in 10% of subjects.

RESULTS

Current disinhibition strongly predicted weight gain and current BMI (partial r = 0.27 and 0.34, respectively, both P < 0.001). Neither restraint nor hunger was a significant independent predictor of either variable, but the positive associations between disinhibition and both weight gain and BMI were attenuated by restraint (P = 0.016 and 0.010, respectively, after adjustment for confounding variables). In the subpopulation of women who reported a stable level of voluntary dietary energy restriction, disinhibition also strongly predicted weight gain and higher BMI, and restraint was negatively associated with weight gain (partial r = -0.17, P = 0.019).

CONCLUSIONS

Higher disinhibition is strongly associated with greater adult weight gain and higher current BMI, and dietary restraint may attenuate this association when disinhibition is high. These findings suggest that eating behavior has an important role in the prevention of adult-onset obesity and that further studies are warranted.

Dietary fiber and weight regulation

The influence of dietary fiber on energy regulation remains controversial. This review summarizes published studies on the effects of dietary fiber on hunger, satiety, energy intake, and body composition in healthy individuals. Under conditions of fixed energy intake, the majority of studies indicate that an increase in either soluble or insoluble fiber intake increases postmeal satiety and decreases subsequent hunger. When energy intake is ad libitum, mean values for published studies indicate that consumption of an additional 14 g/day fiber for >2 days is associated with a 10% decrease in energy intake and body weight loss of 1.9 kg over 3.8 months. Furthermore, obese individuals may exhibit a greater suppression of energy intake and body weight loss (mean energy intake in all studies was reduced to 82% by higher fiber intake in overweight/obese people versus 94% in lean people; body weight loss was 2.4 kg versus 0.8 kg). These amounts are very similar to the mean changes in energy intake and body weight changes observed when dietary fat content is lowered from 38% to 24% of energy intake in controlled studies of nonobese and obese subjects. The observed changes in energy intake and body weight occur both when the fiber is from naturally high-fiber foods and when it is from a fiber supplement. In view of the fact that mean dietary fiber intake in the United States is currently only 15 g/day (i.e., approximately half the American Heart Association recommendation of 25-30 g/day), efforts to increase dietary fiber in individuals consuming <25 g/day may help to decrease the currently high national prevalence of obesity.

Regulation of energy intake may be impaired in nutritionally stunted children from the shantytowns of São Paulo, Brazil

We tested the hypothesis that nutritionally stunted children have impaired regulation of energy intake (EI), a factor that could help explain the increased risk of obesity associated with stunting in developing countries. A 3-d residency study was conducted in 56 prepubertal boys and girls aged 8-11 y from the shantytowns of Sao Paulo, Brazil. Twenty-seven of the subjects were stunted and 29 were not stunted; weight-for-height Z-scores were not significantly different between the groups. Parents of the two groups had equivalent heights and body mass indices. Measurements were made of voluntary EI from a self-selection menu, resting energy expenditure (REE) and body composition. In addition, a 753-kJ yogurt supplement was administered at breakfast on one study day (with an equal number of children receiving the supplement on each of the 3 study days) and its effect on daily EI assessed. There was no change in EI over time in either group (P: = 0.957), and no significant difference in EI between stunted and nonstunted children, even though the stunted children weighed 10% less. Energy intake per kilogram body weight was significantly higher in the stunted children (278 +/- 89 (SD), vs. 333 +/- 67 kJ/kg, P: < 0.05) and EI/REE was also significantly higher (1.91 +/- 0.34 vs. 1.68 +/- 0.38, P: < 0.05). However, the relationship between EI and body weight was not significantly influenced by stunting (P: = 0.12). There was no significant effect of the breakfast supplement on daily EI in either group although the absolute difference in EI between supplement and control days was greater in stunted than in nonstunted children (DeltaEI: +460 +/- 1574 vs. -103 +/- 1916 kJ/d, P: = 0.25). These data provide preliminary evidence consistent with the suggestion that stunted children tend to overeat opportunistically, but further studies are required to confirm these results in a larger study.

Why are nutritionally stunted children at increased risk of obesity? Studies of metabolic rate and fat oxidation in shantytown children from São Paulo, Brazil

BACKGROUND

Previous research suggested that nutritionally stunted children may have increased risk of obesity, but little is known about potential underlying mechanisms.

OBJECTIVE

We sought to test the hypothesis that stunted children have a low metabolic rate and impaired fat oxidation relative to nonstunted children.

DESIGN

The subjects were 58 prepubertal boys and girls aged 8-11 y from the shantytowns of São Paulo, Brazil. Twenty-eight were stunted (height-for-age z score <-1.5) and 30 had similar weight-for-height but normal height (height-for-age z score >-1.5). Parents of children in the 2 groups had equivalent height and body mass index values. Fasting and postprandial energy expenditure, respiratory quotient (RQ), and substrate oxidation were measured with indirect calorimetry in a 3-d resident study in which all food was provided and body composition was measured with dual-energy X-ray absorptiometry.

RESULTS

Stunted children had normal resting energy expenditure relative to body composition compared with control children (4559 +/- 90 and 4755 +/- 86 kJ/d, respectively; P: = 0.14) and had normal postprandial thermogenesis (2.4 +/- 0.3% and 2.0 +/- 0.3% of meal load, respectively; P: = 0.42). However, fasting RQ was significantly higher in the stunted group (0.92 +/- 0.009 compared with 0.89 +/- 0.007; P: = 0.04) and consequently, fasting fat oxidation was significantly lower (25 +/- 2% compared with 34 +/- 2% of energy expenditure; P: < 0.01).

CONCLUSIONS

Childhood nutritional stunting is associated with impaired fat oxidation, a factor that predicted obesity in other at-risk populations. This finding may help explain recent increases in body fatness and the prevalence of obesity among stunted adults and adolescents in developing countries.

Genetic and environmental contributions to obesity

Groups that are already concerned about obesity can be linked together. This can generate plans of action and may lead to small-scale interventions. At the same time, awareness needs to be raised among other potential partners, especially federal, state, and local government agencies. As a partnership is built, funding opportunities, from public and private entities, should increase. The ultimate need is a public health campaign to combat an important public health problem.

Dietary determinants of energy intake and weight regulation in healthy adults

Until recently, the percentage of energy from dietary fat has been considered a primary determinant of body fatness. This review covers recent studies from our laboratory that challenge this notion. High and low fat diets matched for energy density, palatability and fiber resulted in similar mean voluntary energy intakes over 9 d; analysis of the individual foods in these diets showed that energy density and palatability were significant determinants of energy intake, independent of fat content. Path analysis further revealed that the influence of energy density on energy intake was in part direct, and in part indirect and mediated by palatability. In another study, dietary variety within food groups was shown to be an important predictor of body fatness, and the direction of the association depended on which food groups provided the variety, i.e., the variety of sweets, snacks, condiments, entrees and carbohydrates consumed was positively associated with body fatness, whereas the variety of vegetables was negatively associated. Last, a study of restaurant food and body fatness showed that the frequency of consumption of restaurant food was positively associated with body fatness, independent of education level, smoking status, alcohol intake and physical activity. Restaurant meals tend to be high in fat and low in fiber, and thus energy dense. Restaurants also typically serve a variety of palatable foods in large portions. The increasing variety of high energy foods available and the increasing proportion of household income spent on foods consumed away from home may help explain the U.S. national rising prevalence of obesity.

Undereating and underrecording of habitual food intake in obese men: selective underreporting of fat intake

BACKGROUND

Underreporting of food intake is common in obese subjects.

OBJECTIVE

One aim of this study was to assess to what extent underreporting by obese men is explained by underrecording (failure to record in a food diary everything that is consumed) or undereating. Another aim of the study was to find out whether there was an indication for selective underreporting.

DESIGN

Subjects were 30 obese men with a mean (+/-SD) body mass index (in kg/m(2)) of 34 +/- 4. Total food intake was measured over 1 wk. Energy expenditure (EE) was measured with the doubly labeled water method, and water loss was estimated with deuterium-labeled water. Energy balance was checked for by measuring body weight at the start and end of the food-recording week and 1 wk after the recording week.

RESULTS

Mean energy intake and EE were 10.4 +/- 2.5 and 16.7 +/- 2. 4 MJ/d, respectively; underreporting was 37 +/- 16%. The mean body mass loss of 1.0 +/- 1.3 kg over the recording week was significantly different (P < 0.05) from the change in body mass over the nonrecording week, and indicated 26% undereating. Water intake (reported + metabolic water) and water loss were significantly different from each other and indicated 12% underrecording. The reported percentage of energy from fat was a function of the level of underreporting: percentage of energy from fat = 46 - 0.2 x percentage of underreporting (r(2) = 0.28, P = 0.003).

CONCLUSIONS

Total underreporting by the obese men was explained by underrecording and undereating. The obese men selectively underreported fat intake.

Overeating in America: association between restaurant food consumption and body fatness in healthy adult men and women ages 19 to 80

PURPOSE

To examine the association between the frequency of consuming restaurant food and body fatness in adults.

RESEARCH METHODS AND PROCEDURES

Usual free-living dietary intake and the frequency of consuming food from seven different restaurant types (fried chicken, burger, pizza, Chinese, Mexican, fried fish, and "other") were assessed by food frequency questionnaire in 73 healthy men and women [ages 19 to 80, body mass index (BMI) 18 to 33]. In addition, body fatness (percent weight) was determined by hydrostatic weighing, and physical activity and other lifestyle parameters were assessed by questionnaire. The relationship between the frequency of consuming restaurant food and body fatness was determined after controlling for age, sex, and other confounders by using multiple regression techniques.

RESULTS

Restaurant food consumption averaged 7.5+/-8.5 (Standard Deviation) times/month. After controlling for age and sex, the frequency of consuming restaurant food was positively associated with body fatness (partial r = 0.36, p = 0.003). The strength of this association did not change after controlling for education level, smoking status, and alcohol intake, but after additionally controlling for physical activity, the partial r increased to 0.42 (p = 0.004). Total daily intakes of energy, fat, and fiber were significantly associated with restaurant food consumption frequency (r = 0.59, 0.28, and -0.45, respectively, p = 0.02 to 0.0001).

DISCUSSION

The frequency of consuming restaurant food was positively associated with increased body fatness in adults. The increasing proportion of household food income spent on food prepared away from home in the United States may therefore help explain the rising national prevalence of obesity.