1994;14;1751-1760 Arterioscler Thromb Vasc Biol AH Lichtenstein ...

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o IT o o o O o 160 75 BASE- UNE RfOUCED FAT LOW FAT - ENERGY LOW FAT I ENERGY o IT O 125 X o O 100 BASE- LINE REDUCED FAT Lichtenstein et al Low-Fat Diet, Weight Loss, and Plasma Lipids 1755 LOW FAT - ENERGY LOW FAT 1 ENERGY FIQ 1. Une plots of Individual plasma lipid concentrations at the end of each diet phase. See "Methods" for definitions of diets. LDL indicates low-density lipoprotein; HDL, high-density lipoprotein. and Fig 2). Postprandial plasma cholesterol and non- HDL-C concentrations were not significantly different from fasting values. In contrast, HDL-C concentrations consistently exhibited a postprandial fall of 5% to 7%, which was significantly different from fasting levels over all the diet phases. Mean postprandial plasma triglyceride concentrations (at 5-, 8-, and 10-hour time points) were approximately twofold higher than fasting values and were statistically different from fasting values for all diet phases. By 24 hours plasma triglyceride concentrations were statistically indistinguishable from the initial fasting values regardless of dietary treatment. The differences observed among diets with respect to postprandial total cholesterol, non-HDL-C, HDL-C, and triglyceride concentrations were similar to those observed in the fasting state. Postprandial total cholesterol concentrations were from lowest to highest when the subjects consumed the low-fat (j, energy), reducedfat, low-fat (-» energy), and baseline diets. In general, non-HDL-C concentrations were lowest when the subjects consumed the low-fat (| energy) and reduced-fat diets and highest when they consumed the low-fat (-> energy) and baseline diets. HDL-C concentrations were from lowest to highest when the subjects consumed the low-fat (—» energy), low-fat (j energy), reduced fat, and baseline diets. Postprandial triglyceride concentrations were significantly higher at the end of the low-fat (-» energy) diet than at the end of any of the other diet periods. The study subjects continued to consume the low-fat (| energy) diet for an additional 5 weeks (Table 5). Although there was a persistent loss of body weight, albeit at a somewhat slower rate (0.62±0.47 versus 0.43±0.43 per week, first and second diet periods, respectively), the greatest effect of weight loss on plasma lipid and apolipoprotein concentrations occurred after the first 5 weeks of the fourth study period. Plasma lipid and apolipoprotein concentrations remained remarkably stable during the second 5-week period of the low-fat (J. energy) phase. Discussion Impressive observations have been made with respect to the benefits of extremely low-fat diets on plasma lipid concentrations and regression of atherosclerotic plaque. 6 ' 7 ' 58 Populations that normally consume low-fat diets are generally reported to have lower plasma lipid concentrations and rates of coronary heart disease than those consuming higher fat diets. 59 In such populations caloric intake tends to be lower and fiber intake higher than in societies consuming higher fat diets, and obesity is generally not cited as a major public health problem. 5961 In general, the consumption of ad libitum quantities of low-fat diets relative to higher fat diets on an experimental basis is accompanied by weight loss. 45 ' 46 - 6268 Increasing the fat intake of people who habitually consume a low-fat diet has been reported to result in weight gain and adverse effects on plasma lipid concentrations. 69 The results of a recent metaanarysis of studies assessing the relation between weight change and plasma lipid levels concluded that weight loss is associated with an improvement of plasma lipid profiles. 70 Taking these observations into consideration, we investigated the effects of reduced-fat and low-fat diets with and without weight loss on plasma lipid, lipoprotein, and apolipoprotein concentrations. Middle-aged and elderly female and male subjects with plasma LDL-C concentrations that indicated the need for dietary modification were targeted, since this is the group for which recommendations to reduce dietary fat content are frequently made. (Although body mass index was not a screening criterion, the group of subjects participating in the study, qualifying on the basis of having LDL-C levels above 130 mg/dL, had a somewhat elevated mean body mass index [27.0±4.5]). We do not have anthropometric measures of the study subjects, and differences in body fat distribution could have modified the effect of weight loss on their plasma lipid levels. Given that limitation, the results of the investigation suggest, relative to a baseline diet, that when body weight was maintained, reducing the total and saturated fat content of the diet in accordance with the current NCEP step 2 guidelines resulted in a significant decrease in total cholesterol, LDL-C, and HDL-C concentrations. Further reducing the total fat content of the diet under the same conditions also resulted in decreased concentrations of total cholesterol, LDL-C, and HDL-C, although the reductions in total cholesterol and LDL-C were less dramatic and the decrease in HDL-C greater than when the subjects consumed the reduced-fat diet. Accompanying these changes was a striking increase in plasma triglycerides and VLDL cholesterol concentrations. The end result was a less favorable plasma lipid profile with respect to cardiovascular risk. Allowing the subjects to decrease their caloric intake while maintaining the macronutri- Downloaded from http://atvb.ahajournals.org/ by guest on December 7, 2012
1756 Arteriosclerosis and Thrombosis Vol 14, No 11 November 1994 TABLE 4. Postprandial Plasma Upld Response to Three Meals and On* Snack at the End of Each Diet Phase Hours Postprandial 0 5 8 10 24 0 5 8 10 24 0 5 8 10 24 0 5 8 10 24 Baseline 226±32* 224 ±32* 223±34* 225 ±35* 227±35* 179±32* 179±33* 178±36* 180±37* 179±34* 48±11* 45±10* 45+10* 45+9* 48+11* 1O9±31t 174+92t 187±77*t 201 ±82*t 113±39t Reduced Fat 195±19t* 193±17f* 192±17t* 197±22f* 195±21f* 153±16t 153±16t 153±17t 158±21f* 153±18t 43±9t 40±9t 39±8t 39±9t 41±8t 114±30t 180±71t 230±90* 239±142*t 121±38t Total cholesterol Non-HDL-C HDL-C Triglycerides Diet Low Fat (^ Energy) 2O8±22t 209±23*t 208±22*t 207±26*t 210±24*t 172 ±24* 175 ±24* 175 ±25* 173±28*t 174+24* 35±7* 34 + 7* 33+7* 33+7* 36+7* 185+77* 248+113* 243±125* 259+109* 198+83* Low Fat (I Energy) 190±19* 185+20* 182±25* 182±23* 187±23** 152±19t 148±20t 145±23t 144±22t 148±22t 38±8* 37±6t* 37±8t* 37±7f* 39±7t* 129±33t 162±61t 141±51t 152±51t 126±34t HDL-C indicates htgh-density llpoproteln cholesterol; non-HDL-C, total cholesterol minus HDL-C. Values are mean±SD and are expressed in milligrams per deciliter; n=11. See "Methods" for definitions of diets. ANOVA for each time point using data from all four diet groups showed a significant effect of diet (P
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