Low-fat diets are preferred

Can we say what diet is best for health?

Diet is established among the most important influences on health in modern societies. Injudicious diet figures among the leading causes of premature death and chronic disease. Optimal eating is associated with increased life expectancy, dramatic reduction in lifetime risk of all chronic disease, and amelioration of gene expression. In this context, claims abound for the competitive merits of various diets relative to one another. Whereas such claims, particularly when attached to commercial interests, emphasize distinctions, the fundamentals of virtually all eating patterns associated with meaningful evidence of health benefit overlap substantially. There have been no rigorous, long-term studies comparing contenders for best diet laurels using methodology that precludes bias and confounding, and for many reasons such studies are unlikely. In the absence of such direct comparisons, claims for the established superiority of any one specific diet over others are exaggerated. The weight of evidence strongly supports a theme of healthful eating while allowing for variations on that theme. A diet of minimally processed foods close to nature, predominantly plants, is decisively associated with health promotion and disease prevention and is consistent with the salient components of seemingly distinct dietary approaches. Efforts to improve public health through diet are forestalled not for want of knowledge about the optimal feeding of Homo sapiens but for distractions associated with exaggerated claims, and our failure to convert what we reliably know into what we routinely do. Knowledge in this case is not, as of yet, power; would that it were so.

Mediterranean diet and cardiodiabesity: a review

Cardiodiabesity has been used to define and describe the well-known relationship between type 2 Diabetes Mellitus (T2DM), obesity, the metabolic syndrome (MetS) and cardiovascular disease (CVD). The objective of this study was to perform a scientific literature review with a systematic search to examine all the cardiovascular risk factors combined and their relationship with adherence to the Mediterranean Diet (MedDiet) pattern as primary prevention against cardiodiabesity in a holistic approach. Research was conducted using the PubMed database including clinical trials, cross-sectional and prospective cohort studies. Thirty-seven studies were reviewed: fourteen related to obesity, ten to CVD, nine to MetS, and four to T2DM. Indeed 33 provided strong evidence on the association between adherence to a MedDiet and a reduced incidence of collective cardiodiabesity risk in epidemiological studies. This scientific evidence makes the MedDiet pattern very useful for preventive strategies directed at the general population and also highlights the need to consider all these diet-related risk factors and health outcomes together in daily primary care.

Consumption of fried foods and weight gain in a Mediterranean cohort: the SUN project

BACKGROUND AND AIMS

The consumption of fried foods is believed to be linked with obesity and higher weight gain, however, the evidence from long-term randomized trials or prospective epidemiological studies is scarce. Therefore, the aim of our study was to prospectively evaluate the association between the consumption of fried foods and weight change and the incidence of overweight/obesity in a Mediterranean cohort.

METHODS AND RESULTS

Prospective cohort study of 9850 men and women with a mean age of 38.1 years (SD 11.4) were followed-up for a median of 6.1 years to assess average yearly change in body weight, and incidence of overweight/obesity. The consumption of fried foods was associated with higher weight gain, but the differences were of small magnitude and statistically non-significant. The incidence of overweight/obesity during follow-up was also assessed in the subset of 6821 participants with initial body mass index <25 kg/m(2) (initially free of overweight/obesity), after adjusting for potential confounders, the odds ratio for developing overweight/obesity among participants who consumed fried foods >4 times/week was 1.37 (95% confidence interval: 1.08 to 1.73) in comparison with those who consumed fried foods <2 times/week (p for trend = 0.02).

CONCLUSION

In this Mediterranean prospective cohort, a more frequent consumption of fried foods at baseline was associated with a higher risk of subsequently developing overweight/obesity during follow-up.

Effect of Dietary Carbohydrate Source on the Development of Obesity inAgoutiTransgenic Mice**

OBJECTIVES

Our objective was to evaluate the effects of a qualitative change in dietary carbohydrate source on body weight and adiposity in a rodent model of diet-induced obesity.

RESEARCH METHODS AND PROCEDURES

We evaluated the effects of high-fat diets (basal) varying in carbohydrate source in aP2-agouti transgenic mice. In the ad libitum study, animals were given free access to the basal diet or one of four test diets for 6 weeks. In two of the diets, dietary carbohydrate was derived from a single source: mung bean noodles (MUNG) or rolled oats (ROLL). The remaining diets were designed to mimic commercially available instant oatmeal with added sugar (IO-S) or flavored instant oatmeal (IO-F). In the energy-restricted study, animals were given ad libitum access to the basal diet for 6 weeks. Subsequently, animals were assigned to one of six treatment groups for 6 weeks. One group was continued on the basal diet ad libitum. The remaining groups were maintained with energy restriction (70% ad libitum) on either the basal, MUNG, ROLL, IO-S, or IO-F diet.

RESULTS

Subcutaneous fat pad mass was significantly higher (p<0.05) in the energy-restricted basal and IO-S groups compared with the energy-restricted ROLL diet. Similarly, visceral fat pad mass was significantly lower with ROLL and MUNG diets (p<0.05 for both) compared with basal and IO-S diets, and the insulin:glucose ratio was reduced (by 23% to 34%, p<0.05) in these two diets compared with all others. In ad libitum-fed animals, liver fatty acid synthase expression was 43% to 62% lower (p<0.05) with ROLL and MUNG diets compared with all others.

DISCUSSION

These data suggest that a qualitative change in dietary carbohydrate source modulates body weight and adiposity.

Systematic review and meta-analysis of clinical trials of the effects of low carbohydrate diets on cardiovascular risk factors

A systematic review and meta-analysis were carried out to study the effects of low-carbohydrate diet (LCD) on weight loss and cardiovascular risk factors (search performed on PubMed, Cochrane Central Register of Controlled Trials and Scopus databases). A total of 23 reports, corresponding to 17 clinical investigations, were identified as meeting the pre-specified criteria. Meta-analysis carried out on data obtained in 1,141 obese patients, showed the LCD to be associated with significant decreases in body weight (-7.04 kg [95% CI -7.20/-6.88]), body mass index (-2.09 kg m(-2) [95% CI -2.15/-2.04]), abdominal circumference (-5.74 cm [95% CI -6.07/-5.41]), systolic blood pressure (-4.81 mm Hg [95% CI -5.33/-4.29]), diastolic blood pressure (-3.10 mm Hg [95% CI -3.45/-2.74]), plasma triglycerides (-29.71 mg dL(-1) [95% CI -31.99/-27.44]), fasting plasma glucose (-1.05 mg dL(-1) [95% CI -1.67/-0.44]), glycated haemoglobin (-0.21% [95% CI -0.24/-0.18]), plasma insulin (-2.24 micro IU mL(-1) [95% CI -2.65/-1.82]) and plasma C-reactive protein, as well as an increase in high-density lipoprotein cholesterol (1.73 mg dL(-1) [95%CI 1.44/2.01]). Low-density lipoprotein cholesterol and creatinine did not change significantly, whereas limited data exist concerning plasma uric acid. LCD was shown to have favourable effects on body weight and major cardiovascular risk factors; however the effects on long-term health are unknown.

Decision-Making Deficits and Overeating: A Risk Model for Obesity

OBJECTIVE

To demonstrate that human overeating is not just a passive response to salient environmental triggers and powerful physiological drives; it is also about making choices. The ventromedial prefrontal cortex has been strongly implicated in the neural circuitry necessary for making advantageous decisions when various options for action are available. Decision-making deficits have been found in patients with ventromedial prefrontal cortex lesions and in those with substance dependence--impairments that reflect an inability to advantageously assess future consequences. That is, they choose immediate rewards in the face of future long-term negative consequences.

RESEARCH METHODS AND PROCEDURES

We extended this research to the study of overeating and overweight, testing a regression model that predicted that poor decision making (as assessed by a validated computerized gambling task) and a tendency to overeat under stress would correlate with higher BMI in a group of healthy adult women (N = 41) representing a broad range of body weights.

RESULTS

We found statistically significant main effects for both independent variables in the predicted direction (p < 0.05; R2 = 0.35). Indeed, the decision-making impairments across the 100 trials of the computer task were greater in those with high BMI than in previous studies with drug addicts.

DISCUSSION

Findings suggested that cortical and subcortical processes, which regulate one's ability to inhibit short-term rewards when the long-term consequences are deleterious, may also influence eating behaviors in a culture dominated by so many, and such varied, sources of palatable and calorically dense sources of energy.

Food and nutrient intakes and their associations with lower BMI in middle-aged US adults: the International Study of Macro-/Micronutrients and Blood Pressure (INTERMAP)

BACKGROUND

Clinical trial data show that reduction in total energy intake enhances weight loss regardless of the macronutrient composition of the diet. Few studies have documented dietary patterns or nutrient intakes that favor leanness [BMI (in kg/m²) ≤25] in free-living populations.

OBJECTIVE

This investigation examined associations of usual energy, food, and nutrient intakes with BMI among US participants of the International Study of Macro-/Micronutrients and Blood Pressure (INTERMAP).

DESIGN

The INTERMAP is an international cross-sectional study of dietary factors and blood pressure in men and women (ages 40-59 y) that includes 8 US population samples. The present study included data from 1794 Americans who were not consuming a special diet and who provided four 24-h dietary recalls and 2 timed 24-h urine collections. Multivariable linear regression with the residual method was used to adjust for energy intake; sex-specific associations were assessed for dietary intakes and urinary excretions with BMI adjusted for potential confounders including physical activity.

RESULTS

Lower energy intake was associated with lower BMI in both sexes. Univariately, higher intakes of fresh fruit, pasta, and rice and lower intakes of meat were associated with lower BMI; these associations were attenuated in multivariable analyses. Lower urinary sodium and intakes of total and animal protein, dietary cholesterol, saturated fats, and heme iron and higher urinary potassium and intakes of carbohydrates, dietary fiber, and magnesium were associated with lower BMI in both sexes.

CONCLUSION

The consumption of foods higher in nutrient-dense carbohydrate and lower in animal protein and saturated fat is associated with lower total energy intakes, more favorable micronutrient intakes, and lower BMI.

The effects of four hypocaloric diets containing different levels of sucrose or high fructose corn syrup on weight loss and related parameters

Background

The replacement of sucrose with HFCS in food products has been suggested as playing a role in the development of obesity as a public health issue. The objective of this study was to examine the effects of four equally hypocaloric diets containing different levels of sucrose or high fructose corn syrup (HFCS).

Methods

This was a randomized, prospective, double blind trial, with overweight/obese participants measured for body composition and blood chemistry before and after the completion of 12 weeks following a hypocaloric diet. The average caloric deficit achieved on the hypocaloric diets was 309 kcal.

Results

Reductions were observed in all measures of adiposity including body mass, BMI,% body fat, waist circumference and fat mass for all four hypocaloric groups, as well as reductions in the exercise only group for body mass, BMI and waist circumference.

Conclusions

Similar decreases in weight and indices of adiposity are observed when overweight or obese individuals are fed hypocaloric diets containing levels of sucrose or high fructose corn syrup typically consumed by adults in the United States.

Weight loss and lipolysis promote a dynamic immune response in murine adipose tissue

Obesity elicits an immune response characterized by myeloid cell recruitment to key metabolic organs, including adipose tissue. However, the response of immune cells to nonpathologic metabolic stimuli has been less well studied, and the factors that regulate the metabolic-dependent accumulation of immune cells are incompletely understood. Here we characterized the response of adipose tissue macrophages (ATMs) to weight loss and fasting in mice and identified a role for lipolysis in ATM recruitment and accumulation. We found that the immune response to weight loss was dynamic; caloric restriction of high-fat diet-fed mice led to an initial increase in ATM recruitment, whereas ATM content decreased following an extended period of weight loss. The peak in ATM number coincided with the peak in the circulating concentrations of FFA and adipose tissue lipolysis, suggesting that lipolysis drives ATM accumulation. Indeed, fasting or pharmacologically induced lipolysis rapidly increased ATM accumulation, adipose tissue chemoattractant activity, and lipid uptake by ATMs. Conversely, dietary and genetic manipulations that reduced lipolysis decreased ATM accumulation. Depletion of macrophages in adipose tissue cultures increased expression of adipose triglyceride lipase and genes regulated by FFA, and increased lipolysis. These data suggest that local lipid fluxes are central regulators of ATM recruitment and that once recruited, ATMs form lipid-laden macrophages that can buffer local increases in lipid concentration.

The health implications of sucrose, high-fructose corn syrup, and fructose: what do we really know?

The epidemic of obesity and related metabolic diseases continues to extract an enormous health toll. Multiple potential causes for obesity have been suggested, including increased fat consumption, increased carbohydrate consumption, decreased physical activity, and, most recently, increased fructose consumption. Most literature cited in support of arguments suggesting a link between obesity and fructose consumption is epidemiologic and does not establish cause and effect. The causes of obesity are well-known and involve the overconsumption of calories from all sources. Research employing a pure fructose model distorts the real-world situation of fructose consumption, which predominantly comes from sweeteners containing roughly equal proportions of glucose and fructose. The fructose hypothesis has the potential to distract us from further exploration and amelioration of known causes of obesity. Randomized prospective trials of metabolic consequences of fructose consumption at normal population levels and from sources typically found in the human diet such as sucrose and high-fructose corn syrup are urgently needed.

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.)

Carbohydrate quantity and quality in relation to body mass index

The increased prevalence of overweight and obesity in the United States since approximately 1980 is temporally associated with an increase in carbohydrate intake, with no appreciable change in absolute intake of fat. Despite speculation that both carbohydrate quantity and quality have contributed significantly to excess weight gain, the relationship between carbohydrate intake and body mass index (BMI) is controversial. A review of relevant literature indicates that most epidemiologic studies show an inverse relationship between carbohydrate intake and BMI, even when controlling for potential confounders. These observational studies are supported by results from a number of dietary intervention studies wherein modest reductions in body weight were observed with an ad libitum, low-fat, high-carbohydrate diet without emphasis on energy restriction or weight loss. With few exceptions, high glycemic load is associated with lower BMI, even when adjusted for total energy intake. Data on the association between glycemic index and BMI are not as consistent, with more studies showing either no association or an inverse relationship, rather than a positive relationship. Whole-grain intake is generally inversely associated with BMI; refined grain intake is not. Because overall dietary quality tends to be higher for high-carbohydrate diets, a low-fat dietary strategy with emphasis on fiber-rich carbohydrates, particularly cereal fiber, may be beneficial for health and weight control.

Stellenwert der Ernährung bei Adipositas

The goal of good concepts for treating obesity is to achieve sustained changes in lifestyle. Formula diets are in fact superior to hypocaloric diets, but the results of diet only approaches are consistently disappointing. Formula diets or very low calorie diets should thus be undertaken in conjunction with an overall therapeutic concept under a physician's supervision together with psychological and nutritional education as well as guidance in exercise therapy. These treatment strategies can be carried out successfully in the outpatient setting. On a long-term basis, reducing the costs of health care will only be feasible by implementing prevention programs during childhood and adolescence. Preventive measures focusing on nutrition should lay the foundation in kindergartens and schools to control the epidemic-like spread of obesity.

Fast food consumption and breakfast skipping: predictors of weight gain from adolescence to adulthood in a nationally representative sample

PURPOSE

To investigate whether fast food consumption and breakfast skipping are associated with weight gain during the transition from adolescence to adulthood.

METHODS

A prospective study of 9919 adolescents participating in Waves II (age range 11-21 years) and III (age range 18-27 years) of the National Longitudinal Study of Adolescent Health. BMI z scores (zBMI) were computed using the 2000 Centers for Disease Control and Prevention growth charts. Multivariate regression models assessed the relationship between Wave II fast food and breakfast consumption and change in fast food and breakfast consumption between Waves II and III and weight gain during the transition to adulthood.

RESULTS

Marked increases in fast food consumption and decreases in breakfast consumption occurred over the 5-year interval. Greater days of fast food consumption at Wave II predicted increased zBMI at Wave III. Fewer days of breakfast consumption at Wave II and decreases in breakfast consumption between Waves II and III predicted increased zBMI at Wave III.

CONCLUSIONS

Fast food consumption and breakfast skipping increased during the transition to adulthood, and both dietary behaviors are associated with increased weight gain from adolescence to adulthood. These behaviors may be appropriate targets for intervention during this important transition.

Effect of very high-fat diets on body weight, lipoproteins, and glycemic status in the obese

Given the increased prevalence of obesity in the United States, despite reduced fat intake, there has been increasing interest in the effect of dietary fat on body weight, lipoproteins, and glycemic status. Despite predictions from epidemiologic and physiologic studies, recent prospective trials have demonstrated equivalent weight loss on high-fat versus low-fat diets. Nevertheless, the type of dietary fat consumed has substantially different effects on lipoproteins. Saturated fat raises high-density lipoprotein cholesterol but has unfavorable effects on total cholesterol, and has been associated with increased cardiovascular events. In contrast, unsaturated fats, and particularly omega-3 fatty acids, have the combined benefits of lowering serum cholesterol and raising high-density lipoprotein, as well as favorable effects on insulin resistance and inflammation; they also lower cardiovascular events in high-risk patients. Although current national guidelines modestly liberalize unsaturated fat consumption, important questions still remain about the optimal percentage of unsaturated fats in the diet.

Responses of inflammatory markers to a low-fat, high-carbohydrate diet: effects of energy intake

BACKGROUND

Inflammation contributes to atherogenesis. Dietary fats may be proinflammatory.

OBJECTIVE

The objective was to determine whether energy intake modulates the effects of low-fat, high-carbohydrate intakes on inflammatory markers.

DESIGN

Twenty-two healthy postmenopausal women with a mean (+/-SD) age of 61 +/- 11 y, who were not receiving hormone replacement therapy, were fed eucaloric diets to reduce their fat intake from 35% to 15% of energy. Next, the women consumed a 15%-fat ad libitum diet under free-living conditions. Serum highly sensitive C-reactive protein, interleukin 6, HDL serum amyloid A, and adiponectin concentrations were measured at the end of the eucaloric and ad libitum low-fat, high-carbohydrate intakes.

RESULTS

The eucaloric diet decreased adiponectin from 16.3 +/- 2.1 to 14.2 +/- 2.0 mg/L (P < 0.05) and increased triacylglycerol from 131 +/- 11 to 164 +/- 14 mg/dL (P < 0.01). The ad libitum low-fat diet caused 6 kg weight loss and decreased highly sensitive C-reactive protein from 4.3 +/- 0.6 to 2.5 +/- 0.5 mg/L (P < 0.01), decreased HDL serum amyloid A from 10.3 +/- 1.8 to 5.7 +/- 1.3 mg/L (P < 0.001), increased adiponectin from 14.2 +/- 2.0 to 16.3 +/- 1.7 mg/L (P < 0.05), and decreased triacylglycerol from 164 +/- 14 to 137 +/- 15 mg/dL (P < 0.05).

CONCLUSION

During the eucaloric phase, the low-fat, high-carbohydrate diet exerted unfavorable effects on the inflammatory markers. In contrast, the ad libitum low-fat, high-carbohydrate intake caused weight loss and affected inflammatory markers favorably. Thus, the energy content of a low-fat, high-carbohydrate diet determines changes in inflammatory markers.

Primary prevention of diabetes: what can be done and how much can be prevented?

Although it is widely believed that type 2 diabetes mellitus is the result of a complex interplay between genetic and environmental factors, compelling evidence from epidemiologic studies indicates that the current worldwide diabetes epidemic is largely due to changes in diet and lifestyle. Prospective cohort studies and randomized clinical trials have demonstrated that type 2 diabetes can be prevented largely through moderate diet and lifestyle modifications. Excess adiposity is the most important risk factor for diabetes, and thus, maintaining a healthy body weight and avoiding weight gain during adulthood is the cornerstone of diabetes prevention. Increasing physical activity and reducing sedentary behaviors such as prolonged TV watching are important both for maintaining body weight and improving insulin sensitivity. There is increasing evidence that the quality of fat and carbohydrate plays a more important role than does the quantity, and thus, public health strategies should emphasize replacing saturated and trans fats with unsaturated fats and replacing refined grain products with whole grains. Recent studies have also suggested a potential role for coffee, dairy, nuts, magnesium, and calcium in preventing diabetes. Overall, a healthy diet, together with regular physical activity, maintenance of a healthy weight, moderate alcohol consumption, and avoidance of sedentary behaviors and smoking, could nearly eliminate type 2 diabetes. However, there is still a wide gap between what we know and what we practice in the field of public health; how to narrow that gap remains a major public health challenge.

COMPETING DIETARY CLAIMS FOR WEIGHT LOSS: Finding the Forest Through Truculent Trees

In response to an accelerating obesity pandemic, competing weight-loss diets have propagated; those touting carbohydrate restriction are currently most in vogue. Evidence that sustainable weight loss is enhanced by means other than caloric restriction, however, is lacking. Whereas short-term weight loss is consistently achieved by any dietary approach to the restriction of choice and thereby calories, lasting weight control is not. Competing dietary claims imply that fundamental knowledge of dietary pattern and human health is lacking; an extensive literature belies this notion. The same dietary and lifestyle pattern conducive to health promotion is consistently associated with weight control. A bird's eye view of the literature on diet and weight reveals a forest otherwise difficult to discern through the trees. Competing diet claims are diverting attention and resources from what is actually and urgently needed: a dedicated and concerted effort to make the basic dietary pattern known to support both health and weight control more accessible to all.

Lifestyle and dietary modification for prevention of heart failure

This article discusses the factors that contribute most to systolic and diastolic heart failure (HF): ischemic heart disease, hypertension,obesity, diabetes, and nephropathy. Diabetes often follows the insulin resistance syndrome in which obesity and hypertension are combined with dyslipidemia, and obesity is likely causal. Diabetes and hypertension are common causes of nephropathy, which in turn is a common precursor to HF. Insulin resistance, obesity,dyslipidemia, diabetes, and hypertension are risk factors for atherosclerotic coronary disease and left ventricular ischemia. Each is also a risk factor for diastolic dysfunction.

Diet and obesity

PURPOSE OF REVIEW

Obesity continues to increase in the United States and worldwide. There is controversy surrounding different dietary patterns used to promote weight loss, and none has emerged as clearly more effective. This paper briefly reviews the factors that influence energy intake and dietary treatments used to promote weight loss.

RECENT FINDINGS

Increasing portion size, eating away from home, and consuming a variety of high-energy dense foods appear to increase energy intake. Hormonal influences on diet continue to be explored. Very-low-calorie diets and low-carbohydrate diets lead to greater initial weight loss, but long-term results are no better than more moderate calorie-restricted diets. A program using meal replacements appears to lead to weight loss slightly greater than calorie-restricted diets and offers one option to treat obesity. Dietary patterns low in energy density and glycemic index have potential in treating obesity and should be studied further.

SUMMARY

Clearly, a dietary pattern that prescribes a lower total energy intake is necessary for weight loss, and this pattern should be sustainable to maintain weight loss. Although many dietary programs can achieve short-term loss of weight, dietary treatment should be recommended that emphasizes lifestyle changes and is consistent with other dietary guidelines to promote long-term health. Features consistent with this are a dietary pattern low in total calories, saturated fat, and refined carbohydrate; moderate in whole grains; and high in low-energy dense vegetables and fruits. Future studies should explore dietary strategies and combination therapies that contribute to weight loss, long-term weight maintenance, and improved health.

Diet composition and the metabolic syndrome: what is the optimal fat intake?

Two cholesterol-raising fatty acids in the diet, saturated fatty acids and trans fatty acids, increase the serum low-density lipoprotein cholesterol concentration. This fact justifies the recommendation of a reduced intake of cholesterol-raising fatty acids. Emerging data suggest that diets higher in unsaturated fatty acids, particularly monounsaturated fatty acids, have several advantages over high-carbohydrate intakes. This advantage appears to hold, particularly for populations having a high prevalence of insulin resistance, such as the US population. If the US public were to modify its eating habits in the direction of better weight control and more exercise, higher intakes of carbohydrate might be better tolerated. At the same time, the experience with the Mediterranean population reveals that in healthier populations, diets relatively high in unsaturated fatty acids are well tolerated and are associated with a low prevalence of both coronary heart disease and type 2 diabetes.