Effect of dietary macronutrient composition under moderate hypocaloric intake on maternal adaptation during lactation.
BACKGROUND
No evidence-based recommendations exist concerning what dietary macronutrient composition optimizes weight loss during lactation while maintaining milk production.


OBJECTIVE
The study was designed to test the following hypotheses: compared with a reduced-calorie, high-carbohydrate (H-CHO) diet, an isonitrogenous, isocaloric high-fat (H-F) diet will decrease milk production and carbohydrate oxidation, increase gluconeogenesis and hexoneogenesis, and not affect energy balance.


METHODS
Seven healthy lactating mothers and their infants were studied on 2 occasions in random order for 8 d separated by 1-2 wk. On one occasion, the subjects received the H-F (30% of energy as carbohydrate and 55% as fat) diet and on the other occasion received the H-CHO (60% of energy as carbohydrate and 25% as fat) diet. Milk production, infant intakes, and substrate and hormone concentrations were measured. Glucose rates of appearance, production, gluconeogenesis, glycogenolysis, and hexoneogenesis were measured by using stable-isotope gas chromatography-mass spectrometric techniques, and energy expenditure and substrate oxidation were measured by using indirect calorimetry.


RESULTS
Milk volume, lactose, and protein concentrations were unaffected. Milk fat, energy, and infant intakes were higher (P < 0.05) during the H-F diet. Neither gluconeogenesis nor hexoneogenesis was different. During the H-F diet, energy expenditure and fat and protein oxidation rates were higher (P < 0.05), and the daily energy balance deficit was greater (P < 0.01).


CONCLUSIONS
Milk fat, energy output, and energy expenditure were higher during the H-F diet, which resulted in a greater negative energy balance. The lactating mothers adapted to a low carbohydrate intake by decreasing carbohydrate oxidation. Additional studies are warranted to determine whether a hypocaloric H-F diet might promote weight loss to a greater extent than the H-CHO diet while maintaining milk production.
Mohammad
Mahmoud A
MA
Department of Pediatrics, Children's Nutrition Research Center, US Department of Agriculture, Agricultural Research Service, Baylor College of Medicine, Houston, TX 77030-2600, USA.
Sunehag
Agneta L
AL
Haymond
Morey W
MW
D000328:Adult; D001786:Blood Glucose / Q000378:metabolism; D031204:Caloric Restriction; D004038:Diet, Reducing / Q000379:methods; D004040:Dietary Carbohydrates / Q000008:administration & dosage* / Q000378:metabolism; D004041:Dietary Fats / Q000008:administration & dosage* / Q000378:metabolism; D004044:Dietary Proteins / Q000378:metabolism; D002149:Energy Intake; D004734:Energy Metabolism; D005260:Female; D005943:Gluconeogenesis; D006801:Humans; D007223:Infant; D007328:Insulin / Q000097:blood; D007774:Lactation / Q000378:metabolism* / Q000502:physiology; D008895:Milk, Human / Q000378:metabolism*; D010084:Oxidation-Reduction; D015431:Weight Loss / Q000502:physiology*
D001786:Blood Glucose; D004040:Dietary Carbohydrates; D004041:Dietary Fats; D004044:Dietary Proteins; D007328:Insulin