Milk. Most of us drink it – at home, at school, and at work. Thirty years ago, we were told to lower our fat intake – therefore, many of us opted for skim. For those of us who cannot stand the taste of skim, we go for 1% or 2%. Aside from limiting fat intake, low fat milk has fewer calories. And a calorie is a calorie (sarcastic wink). As quickly as we are able to, we have our children drinking the same. It’s healthier, right? Plus, who wants to buy 2 or 3 different kinds of milk? Who drinks whole milk anymore?
I do. My family does. My patients who listen to me do as well. We know that a calorie is NOT a calorie. We know that low fat is a BUST when it comes to maintaining a healthy weight status and a foundation for wellness.
Let’s examine the path that too many children follow when it comes to milk consumption. First, most parents and healthcare professionals are aware that breastfeeding is the preferred method of feeding newborns. Breast milk is the superior source of nutrition for newborns and infants. If we are unable to breastfeed, we choose a formula which is similar in terms of fat composition to breast milk. Even the companies who make our formulas acknowledge breast milk is preferable. Accordingly, each likes to portray its product as the closest thing to breastmilk with the exception of, well, breast milk.
Once our children reach 12 months, it is common to switch from formula or breast milk over to whole milk. It is cheaper and the G.I. tracts of our infants are better able to tolerate cows milk at that age. Pediatricians recommend using whole milk from 12 months until age 2. The reasoning behind this is to ensure adequate growth and central nervous system/brain development. After age 2, the prevailing consensus is to switch to a lower fat milk (2%, 1%, or skim).
Next, let’s look at the fat content of each type of milk (listed in g/100ml)
1. Human breast milk – 4.5g (average)
2. Standard formula – between 3.5 and 4.5g
3. Whole Cow’s Milk – 3.8g
4. 2% Cow’s Milk – 2.0g
5. 1% Cow’s Milk – 1.0g
6. Skim Milk – 0.3g
Is the change to a lower fat milk truly beneficial for our children? Does low fat milk limit BMI growth velocity? What do we really know about CNS/brain development that would lead us to believe 24 months is an appropriate point to limit normal diatary fat in a child’s diet? Have you ever wondered why, when it comes to fat content, it makes sense to suddenly deviate from nature’s best (breast milk) in our preschool age children? I’ve wondered. Likewise, how does this change alter the growth patterns and developmental course for our young people? I wonder about that too.
Now lets look at what evidence is currently available. With regards to growth and specifically weight gain, we know that there is overwhelming evidence that normal dietary fat is not the culprit in our child obesity pandemic. The evidence, in fact, points to fast carbohydrates and sugar. Since milk is a major dietary constituent for most children, shouldn’t we closely examine the “low-fat milk” theory? One recently published study does just that:
As the study indicates, consumption of low fat milk is associated with weight gain and BMI increase. Increasing fat content in the type of milk consumed was inversely associated with BMI score. Since this is a cohort study, there is plenty of room for interpretation. Accordingly, in the discussion section of the study, the authors hypothesize that perhaps parents of overweight children were more likely to use lower fat milk. However, further along in the discussion of the paper, the authors do acknowledge that there is “prospective research which associates whole milk intake with lower BMI than low-fat milk intake. At least theoretically high-fat milk intake may result in less weight gain if its consumption leads to an overall decrease in calories consumed. The presence of fat can induce satiety through the release of cholecystokinin (CCK) and other factors. This could potentially lower appetite for other calorically dense foods…”
The results of the study and its discussion should not surprise anyone who has kept up with the latest in nutritional research. We understand the basic physiological principles at play. Normal dietary fat does NOT activate release of the the fat storage hormone insulin. In addition, it does mediate satiety through CCK and leptin (which act synergistically to reduce body weight). The idea that whole milk would decrease BMI growth velocity makes perfect sense. The study supports this and certainly is a good starting point. In order to determine the longterm impact on BMI change of low-fat vs. whole milk consumption in our children, we need to conduct controlled studies – studies that, to my knowledge, have not been performed. Alas, given the declining health status of our children today, this particular RCT is long overdue.