What affects the amount of fat or calories in mom’s milk?

By Kelly Bonyata, IBCLC

Average calorie & fat content of human milk

The average calorie content of human milk is 22 kcal/oz. Caloric content varies widely throughout each feeding and the day, however, due to changing fat content. The amount of fat in human milk changes dramatically during each feeding and throughout the day, since fat content depends on the degree of emptyness of the breast (empty breast = high fat, full breast = low fat). The average fat content of human milk is 1.2 grams/oz.

Calorie & Fat Content of Human Milk
  Average Range
Energy 22 kcal/oz 13 – 35 kcal/oz
75 kcal/100 mL 45 – 119 kcal/100 mL
Fat (total lipids) 1.2 g/oz 0.6 – 1.5 g/oz
4.2 g/100 mL 2 – 5 g/100 mL
3-5% 1-10%
Hamosh 1991, p. 118; Jelliffe & Jelliffe 1978; Lawrence 1999, p. 108, 305, 738.

What affects the amount of fat and calories in a mother’s milk?

  • Mom’s diet? The research tells us that mom’s diet doesnotaffect the average amount of fat or calories in her milk. However, mom can change the types of fat in her milk by altering the types of fats that she eats (Lawrence 1999, p. 106-113, 300-305; Hamosh 1996, Hamosh 1991, p. 123-124). An increase of one fatty acid could generally be expected to occur concurrently with a decrease in another. For example, one study has shown that black mothers in South Africa who eat a traditional maize diet have less monunsaturated fatty acid in their milk than urban mothers who consumed more animal proteins and fats (van der Westhuyzen 1988).
  • The degree of emptiness of the breast is what research has shown to drive breastmilk fat content, and thus calorie content. The fuller the breast, the lower the fat content of the milk; The emptier the breast, the higher the fat content of the milk (Daly 1993). For more information see I’m confused about foremilk and hindmilk – how does this work? and How does milk production work?
    * FULL
     =  LOWER
    & SLOWER
    * EMPTY
     =  HIGHER
    & FASTER
  • Breast compression has been shown to increase fat content of milk (Stutte 1988). See Breast compression for more information.


The above information tells us that milk fat may be more effectively increased through ‘mechanical’means (i.e. longer & more frequent feeding, massage, breast compression, expressing foremilk before nursing) than by changing mom’s diet.

See How might I increase baby’s weight gain? for details on increasing baby’s intake at the breast. 

Does the amount of fat in mom’s milk make a difference when it comes to baby’s growth?

The research tells us that baby’s milk intake (the volume of milk – not the amount of fat in that milk) is the only thing that has been correlated with infant growth in exclusively breastfed babies. As noted earlier, average fat content of human milk is highly variable, but has not proven to be significant when calculating baby’s total energy intake or weight gain. (Aksit 2002, Butte 1984, Cregan 1999, Mitoulas 2003, Mitoulas 2002.)

Decreasing milk fat?

It has been necessary in rare instances to decrease the fat content of breastmilk for certain medical conditions in baby (chylothorax). Here is information on using a centrifuge to defat human milk:

Note: Never ever try to decrease the fat in your milk (or put baby on a “diet” in any other way) unless baby has a life-threatening medical condition that requires this. The links above refer to such a situation and I included them in case anyone else encountered something similar. Babies and toddlers need fat for brain growth. If you are worried that your breastfed baby is gaining too much weight, see Is my exclusively breastfed baby gaining too much weight? 

Additional Information

@ kellymom

@ other websites


Aksit S, Ozkayin N, Caglayan S. Effect of sucking characteristics on breast milk creamatocrit. Paediatr Perinat Epidemiol. 2002 Oct;16(4):355-60.

Butte NF, Garza C, Smith EO, Nichols BL. Human milk intake and growth in exclusively breast-fed infants. J Pediatr. 1984 Feb;104(2):187-95.

Cregan MD, Hartmann PE. Computerized breast measurement from conception to weaning: clinical implications. J Hum Lact. 1999 Jun;15(2):89-96.

Daly SEJ, DiRosso A, Owens RA, Hartmann PE. Degree of breast emptying explains changes in the fat content, but not fatty acid composition, of human milk. Exp Physiol 1993;78:741-55.

Hamosh M. Breastfeeding: Unraveling the Mysteries of Mother’s Milk. Medscape Women’s Health eJournal 1996;1(5).

Hamosh M, Dewey, Garza C, et al: Nutrition During Lactation. Institute of Medicine, Washington, DC; National Academy Press 1991. This book is available free from the HRSA Information Center (look under Nutrition publications).

Jelliffe DB, Jelliffe EFP. Human milk in the modern world: psychosocial, nutritional and economic significance. Oxford: Oxford University Press, 1978.

Lawrence R and Lawrence R. Breastfeeding: A Guide for the Medical Profession, 5th ed. St. Louis: Mosby, 1999.

Mitoulas LR, Gurrin LC, Doherty DA, Sherriff JL, Hartmann PE. Infant intake of fatty acids from human milk over the first year of lactation. Br J Nutr. 2003 Nov;90(5):979-86.

Mitoulas LR, Kent JC, Cox DB, Owens RA, Sherriff JL, Hartmann PE. Variation in fat, lactose and protein in human milk over 24 h and throughout the first year of lactation. Br J Nutr. 2002 Jul;88(1):29-37.

Stutte PC, et al. The effects of breast massage on volume and fat content of
human milk. Genesis 1988; 10:22-25.

van der Westhuyzen J, Chetty N, Atkinson PM. Fatty acid composition of human milk from South African black mothers consuming a traditional maize diet. Eur J Clin Nutr 1988 Mar;42(3):213-20

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