Effect of dietary macronutrient composition under moderate hypocaloric intake on maternal adaptation during lactation

Am J Clin Nutr. 2009 Jun;89(6):1821-7. doi: 10.3945/ajcn.2008.26877. Epub 2009 Apr 22.


Background: No evidence-based recommendations exist concerning what dietary macronutrient composition optimizes weight loss during lactation while maintaining milk production.

Objectives: 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.

Design: 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.

Publication types

  • Randomized Controlled Trial
  • Research Support, N.I.H., Extramural

MeSH terms

  • Adult
  • Blood Glucose / metabolism
  • Caloric Restriction*
  • Diet, Reducing / methods
  • Dietary Carbohydrates / administration & dosage*
  • Dietary Carbohydrates / metabolism
  • Dietary Fats / administration & dosage*
  • Dietary Fats / metabolism
  • Dietary Proteins / metabolism
  • Energy Intake
  • Energy Metabolism
  • Female
  • Gluconeogenesis
  • Humans
  • Infant
  • Insulin / blood
  • Lactation / metabolism*
  • Lactation / physiology
  • Milk, Human / metabolism*
  • Oxidation-Reduction
  • Weight Loss / physiology*


  • Blood Glucose
  • Dietary Carbohydrates
  • Dietary Fats
  • Dietary Proteins
  • Insulin