Original Article

International Journal of Obesity (2006) 30, 774–781. doi:10.1038/sj.ijo.0803155; published online 29 November 2005

The impact of the covert manipulation of macronutrient intake on energy intake and the variability in daily food intake in nonobese men

W V Rumpler1, M Kramer1, D G Rhodes1 and D R Paul1

1Diet and Human Performance Laboratory, Beltsville Human Nutrition Research Center, BARC-east, Beltsville, MD, USA

Correspondence: Dr WV Rumpler, Diet and Human Performance Laboratory, Beltsville Human Nutrition Research Center, BARC-east, Beltsville, MD, 20705, USA. E-mail: rumpler@bhnrc.arsusda.gov

Received 2 June 2005; Revised 3 August 2005; Accepted 10 September 2005; Published online 29 November 2005.

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Abstract

Objective:

 

To investigate the effect of macronutrient composition on ad libitum food intake in nonobese men.

Design:

 

Balanced, incomplete-block, crossover study where subjects received two of three treatments. Macronutrient composition was manipulated by providing 2.1 MJ/day high-carbohydrate (CHO), high-fat (FAT), and/or high-protein (PRO) drinks every day over the course of two, 8-week periods.

Subjects:

 

In all, 12 healthy normal weight men (age: 39plusminus9 years, BMI: 24.1plusminus1.4 kg/m2).

Measurements:

 

Ad libitum food intake was measured continuously for 16 weeks at the Beltsville Human Nutrition Research Center (BHNRC). Body composition (DEXA) and body weight were also measured.

Results:

 

Average energy intake (EI) during weeks 1 and 2 was lower for CHO than FAT (P<0.05), but this effect disappeared by week 3. EI during CHO increased by 11% from week 1 to 8 through the increased selection of carbohydrate and protein-containing foods, but not fat foods. Food intake was variable, both between and within subjects, but was not related to macronutrient composition.

Conclusion:

 

EI appears to be influenced by macronutrient composition in the short-term when diets are modified, but the effect dissipates in a few weeks if the diet is maintained. These data suggest the presence of macronutrient-specific regulatory mechanisms in the body, but do not support the notion that a high intake of any of the three macronutrients suppresses EI over a prolonged period of time. The high variability in food intake does not appear to be related to macronutrient composition.

Keywords:

food intake, body weight regulation, energy balance, fat, carbohydrate, protein

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