The 500 kcalorie question: can you lose weight from breastfeeding?

A recent publication from the New York State Department of Health contained a single bullet point that has attracted some attention in the last month on the internet. On page 2 of the leaflet, the second point under their section about benefits for mothers is that breastfeeding “burns about 500 calories a day, so you lose the weight you gained more easily”.

Calculating the energy needs for breastfeeding can be done rather simply. Mature milk is generally regarded to have an energy content of 67 kcal/100ml, and exclusively breastfeeding women produce about 700 – 900 ml milk per day, so doing the sums ends up at 469 – 603 kcal. It is good to keep in mind that producing milk isn’t 100% efficient, so that means that more energy than this is needed to produce the milk. A textbook I have (Human Nutrition, Geissler and Powers, 11th Ed., page 315) estimates the efficiency to be around 94%, so this would increase the energy needs for the production of milk to be 500 – 640 kcal per day.

So the estimate from the NYC DOH seems to be a little on the low side, however pregnancy weight gain guidelines normally err on the side of caution and include around 3kg extra fat retained at birth. The recommendations allow for a gradual reduction in this extra fat during the breastfeeding period. Some scientists have also found that lactating women have a reduced metabolic rate compared to before they were pregnant, due to a reduction in muscle mass during pregnancy.

A useful tool for calculating energy needs during breastfeeding is at the US Department of Agriculture’s MyPyramid website. It lets you get an estimate of how many calories you need to eat in a day, and includes a basic diet plan as well. I just punched in my values, and they recommend 2400 kcal in the first six months, and 2600 up to one year if I continue, which is about 500 kcal more than what I normally eat. So this could be a way for me to lose any extra baby pounds I may have picked up during my pregnancy.

What have your experiences been when eating for two? Are the guidelines realistic?

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What is in breastmilk?

Last post I looked a little into the benefits of breastfeeding and the evidence behind one of the claims. This time, I thought it would be interesting to look at the composition of breastmilk, and why it is so hard for infant formula to replicate the same mix.

According to this article by Prentice, colostrum and mature milk contain the following components per 100 ml: 

Substance Unit Amount in colostrum Amount in mature milk
Calories Kcal 55 67
Fat g 2.9 4.2
Lactose g 5.3 7.0
Total protein g 2 1.1
Secretory IgA g 0.5 0.1
Lactoferrin g 0.5 0.2
Casein g 0.5 0.4
Calcium mg 28 30
Sodium mg 48 15
Vitamin A mcg  retinol equivalents 151 75
Vitamin B1 mcg 2 14
Vitamin B2 mcg 30 40
Vitamin C mcg 6 5

BUT, those are just some of the defined substances that we can measure easily!

It also contains things like antimicrobial factors, growth factors, cytokines and anti-inflammatory factors, digestive enzymes, hormones, transporters, and nucleotides. There are also substances in there called oligosaccharides (at least 130 different types, and in high amounts) and other food components such as the carotenoids. Human milk also has a varying flavour that is affected by the diet of the lactating woman. For example, garlic, mint and vanilla flavours are transferred to breastmilk. This is why breastfeeding is recommended. It is impossible for manufacturers of infant formula to make a product that matches human milk for all these extra components, particularly given the cost constraints. Also, since breastmilk is so complex, we are a long way from understanding the short and longterm health consequences of all the individual components.

Breastmilk is amazing stuff!

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Why breastfeed? A closer look at some of the evidence

In the USA, exclusive breastfeeding for the first 6 months of life is regarded as the best strategy for feeding a newborn, the other option being partial or complete formula feeding. The US Department of Health and Human services states the following reasons why breastfeeding is better for babies:

  • Milk adapts to the babies’ needs.
  • Breast milk is easier to digest than formula.
  • Breastfeeding protects infants from infectious and non-communicable disease. Infectious diseases include respiratory infections, and this protection is presumably from the antibodies in colostrum. The non-infectious diseases mention run the gamut from atopic dermatitis and asthma to childhood leukemia.

For mothers, breastfeeding also has the following benefits:

  • There is no formula to prepare or bottles to sterilise.
  • It is around $1500 per year cheaper than formula, and healthcare costs are lower because babies are sick less often.
  • It encourages bonding.
  • Mothers who have breastfed have a lower risk of some diseases like diabetes, breast and ovarian cancer, and postpartum depression.

Since I am a skeptic at heart, I decided to look more in-depth at the evidence behind the recommendations. I did a poor man’s literature review: I searched the well-known scientific journal database, Pubmed, to find the last five publications that investigated breastfeeding and the incidence of infections.

Paper 1: Exclusive breastfeeding protects against acute respiratory infections in Greek infants

The research group looked at the incidence of infectious episodes in 926 infants over their first year of life. 17% of the mothers still breastfed at 6 months.  There were almost 4000 episodes of an infectious illness recorded during the study, and 96% of infants had at least one episode. Infants exclusively breastfed for 6 months had a statistically significant reduction in the number of acute respiratory infections, 50% compared with 65%. There were also trends for reduced ear infections, gastroenteritis, conjunctivitis, thrush and any hospitalisation in their model. Bottom line: breastfeeding for 6 months was associated with fewer respiratory infections.

Paper 2: Breastfeeding reduces hospital admissions in the first six months of life for infants in Hong Kong

The researchers followed 8327 children for 8 years in a population study. They looked at children exclusively breastfed for the first 3 months of life. I don’t have access to the full paper via my university journal log in, so I can’t report on the rates of breastfeeding or disease in the group studied. The study showed that there was a statistically significant reduction in the number of hospitalisations for respiratory tract infections, and any infection, during the first 6 months of life. Bottom line: breastfeeding for 3 months was associated with fewer hospitalisations for any infection, and respiratory tract infection.

Paper 3: Breastfeeding reduces the risk of infections in Dutch infants

This third group of researchers had a cohort of 4164 infants as part of a larger study. 34% of mothers breastfed for 6 months. 48% of infants had a respiratory tract infection, and 8% had a gastrointestinal tract infection. Breastfeeding for at least 6 months was associated with a statistically significant reduced risk of both upper and lower respiratory tract infections and gastrointestinal tract infections according to their model. Infants breastfed for only 4 months or up to 6 months didn’t have this reduced risk. The associations were stronger for exclusive breastfeeding. Bottom line: Breastfeeding for 6 months+ reduced incidence of respiratory and gastrointestinal tract infections

Paper 4: Breastfeeding associated with reduced ear infections but not respiratory tract infections in Finnish infants

This fourth paper looked at 594 infants in childcare centers in Finland. It was cross-sectional rather than prospective like the previous three articles, so the researchers could only link prior breastfeeding with infections in children aged from 1 to 6 years. There was a highly statistically significant reduced incidence of recurrent  ear infections in children, but not with respiratory tract infections. Bottom line: Breastfeeding more than 6 months is associated with reduced ear infections in children aged 1 to 6

Paper 5: Formula-fed infants more likely to be hospitalised for infectious disease

Now a paper from the Philippines. This case-control study matched hospitalised infants with control infants and compared rates of breastfeeding. Infants who were hospitalised were on average 8 weeks old at the time of the study, compared to 10 weeks for the control group. Exclusive breastfeeding rates were similar at around 21% however 33% of the hospitalised infants were exclusively formula fed compared to only 15% of the control infants. Exclusively formula fed infants had a risk almost 4 times the rate of exclusively breastfed infants for any infection, and diarrhea. Bottom line: formula feeding is associated with increased infectious disease and diarrhea compared to breastfed infants

Summary: The latest scientific publications, chosen arbitrarily as the last five published in Pubmed, support the recommendation that breastfeeding reduces some infectious illnesses in infants.


1) Ladomenou F, Moschandreas J, Kafatos A, Tselentis Y, Galanakis E. Protective effect of exclusive breastfeeding against infections during infancy: a prospective study. Arch Dis Child. 2010 Sep 27.

2) Tarrant M, Kwok MK, Lam TH, Leung GM, Schooling CM. Breast-feeding and Childhood Hospitalizations for Infections. Epidemiology. 2010 Sep 22.

3) Duijts L, Jaddoe VW, Hofman A, Moll HA. Prolonged and exclusive breastfeeding reduces the risk of infectious diseases in infancy. Pediatrics. 2010 Jul;126(1):e18-25.

4) Hatakka K, Piirainen L, Pohjavuori S, Poussa T, Savilahti E, Korpela R. Factors associated with acute respiratory illness in day care children. Scand J Infect Dis. 2010 Sep;42(9):704-11.

5) Hengstermann S, Mantaring JB 3rd, Sobel HL, Borja VE, Basilio J, Iellamo AD, Nyunt-U S. Formula feeding is associated with increased hospital admissions due to infections among infants younger than 6 months in Manila, Philippines. J Hum Lact. 2010 Feb;26(1):19-25.

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The ABCs of this Breastfeeding Blog

Breastfeeding is widely promoted as being the best nutrition for a newborn baby. Since I am currently studying Life Span nutrition, and I also am expecting a baby in one month’s time, I thought that these two events would provide the perfect backdrop to a breastfeeding nutrition blog. My coursework provides me with a lot of detailed information about lactation that would not be covered in standard information provided by lactation consultants. Additionally, my initial experiences will provide realistic perspectives on breastfeeding that only experience can provide. I would be able to share with the world both the background information to breastfeeding that I am learning, combined with my own experiences after my baby arrives and I attempt to follow the guidelines.

The topics I wanted to cover include:

  • International breastfeeding recommendations.
  • Recommended energy intakes during lactation and how it is calculated.
  • Breast milk composition and how it is modified by the diet.
  • A closer look at the evidence behind the benefits of breastfeeding.
  • My own experiences putting the guidelines into practise.

So visit regularly for my insights into nutrition for lactation!

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