Elsevier

Nutrition

Volume 22, Issue 6, June 2006, Pages 585-592
Nutrition

Applied nutritional investigation
Effects of peanut oil load on energy expenditure, body composition, lipid profile, and appetite in lean and overweight adults

https://doi.org/10.1016/j.nut.2006.03.012Get rights and content

Abstract

Objective

We evaluated the effects of peanut oil intake on appetite, energy expenditure, body composition, and lipid profile in lean and overweight adults.

Methods

In a parallel-arm, long-term feeding trial, lean and overweight participants received a daily peanut oil load in a milk shake equivalent to 30% of their resting energy expenditure for 8 wk. Forty-eight adults (24 lean and 24 overweight, 12 male and 12 female in each group) completed the protocol. Anthropometric indices, appetite, dietary intake, energy expenditure, and plasma lipids were monitored.

Results

Energy intake increased significantly in the overweight but not in the lean participants. A statistically significant body weight gain (median 2.35 kg) was also observed among the overweight subjects, although this corresponded to only 43% of the theoretical weight gain. Among overweight subjects, high-density lipoprotein cholesterol increased significantly and low-density lipoprotein cholesterol decreased at week 4, but neither concentration was significantly different from baseline at week 8. Similar, but less marked, changes were observed in lean subjects. Resting energy expenditure was 5% greater (P < 0.01) in the overweight group, but no significant difference was observed in the lean subjects. No marked differences of appetite were observed over time in either group or between overweight and lean participants.

Conclusion

These data indicate that ingestion of peanut oil elicits a weaker compensatory dietary response among overweight compared with lean individuals. Body weight increased, albeit less than theoretically predicted. The weaker effect of whole nuts on body weight reported in previous studies suggests components other than oil may be responsible.

Introduction

Cardiovascular disease, diabetes, and high blood pressure will account for 75% of all deaths in developing nations by the year 2020, according to the World Health Organization [1]. Obesity is a risk factor for these disorders [2] and its prevalence has increased markedly over the past 25 y [3]. The prevention and management of overweight/obesity is a public health priority because it is expected to decrease the occurrence and complications of comorbidities.

Dietary guidance aimed at prevention of weight gain frequently includes a limitation on consumption of energy-dense foods in an attempt to limit total caloric intake. Despite their high energy density, inclusion of nuts in the diet is not associated with body weight gain [4], [5], [6], [7], [8], [9], [10]. Several factors may account for this observation. The high satiety value of nuts and noted inefficiencies in nut energy absorption may result in reduced total energy intake and fat bioaccessibility [11], [12], [13], [14]. Monounsaturated fatty acids (MUFAs) and protein content of peanuts may increase resting metabolic rate and diet-induced thermogenesis (DIT) [10], [15], [16]. This would decrease energy deposition in the body.

The fatty acid composition of nuts may also have beneficial effects on blood lipid profiles. Substitution of dietary saturated fatty acids (SFAs) with MUFAs leads to increased high-density lipoprotein (HDL) cholesterol and decreased low-density lipoprotein (LDL) cholesterol, triacylglycerol (TAG), lipid oxidation, and LDL susceptibility to oxidation [5], [17], [18]. Dietary MUFA has also been shown to elicit a smaller postprandial lipemic response [19] with lower chylomicron remnant concentration [20]. Addition of peanuts or other MUFA-rich nuts to the diet significantly improves the blood lipid profile [6], [21].

The effects of peanut oil on satiety are not well characterized. Studies in rats have shown that unsaturated fats, which comprise approximately 40% [22] of a peanut’s energy content, elicit stronger satiety effects than do saturated fats [23]. This suggests that substitution of dietary saturated fat with peanuts could aid in appetite management. However, limited evidence has failed to support a stronger effect of peanut oil on appetite than other fat sources [24], [25]. It is not clear whether the lean and overweight differ in appetitive responses to dietary challenges, especially for high-energy density foods, such as nuts and peanuts. Therefore, the present study evaluated the effects of peanut oil (high in MUFAs) on appetite, body weight, energy expenditure, body composition, and lipid profile in lean and overweight individuals.

Section snippets

Subjects

Forty-eight healthy, non-smoking men (n = 24) and women (n = 24) 18 to 50 y of age completed the study (Table 1). Fifty percent of participants were lean (body mass index <25 kg/m2) and 50% were overweight (body mass index 25–30 kg/m2). The 24 overweight subjects were recruited in the Universidade Federal de Viçosa (Viçosa, Brazil) and the 24 lean subjects were recruited from Purdue University (West Lafayette, IN, USA), the Food Research Institute (Accra, Ghana), and Universidade Federal de

Dietary assessment

Energy and nutrient intakes of lean and overweight subjects are listed in Table 1. Median energy intake of the lean participants tended to be higher during weeks 4 and 8 compared with baseline, but not significantly. Lean participants compensated for 66% of the oil load. In contrast, energy intake was significantly higher than baseline in the overweight group at weeks 4 and 8. This group had a very weak compensatory dietary response (4%). For lean and overweight participants, dietary fat was

Discussion

Epidemiologic studies and clinical interventions have shown that nut consumption is associated with stable or lower body weight [4], [5], [10], [19], [34], [35]. The present study indicates that peanut oil ingestion, at a level of 30% of REE, leads to a significant increase in body weight (∼2.4 kg) among overweight individuals. The increment is attributable largely to increased fat mass. The mean change for the lean participants was slightly larger (∼2.6 kg) but, due to greater variance, was

Conclusion

Data support beneficial effects of peanuts on lipid profiles and a limited effect on energy balance. The influence of peanut fatty acid composition was hypothesized to explain it, but data failed to support this view. These data also showed differential responses of lean and overweight individuals to peanut oil ingestion.

Acknowledgments

The authors thank Amy Devitt for thoughtful suggestions and editing.

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    This work was supported by USAID Prime Agreement No. LAG-G-00-96-00013-00 under the University of Georgia Subcontract No. RC710-013/4092094 (Peanut CRSP).

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