Research Review: Milk for fat loss?
Can milk as a post-work out drink lead to more fat lost than a carb post-work out drink?
Old-school bodybuilders know the formula:
This is pretty much the exact opposite of what most women want. They want to avoid getting too muscular and get small instead. So they avoid squats and milk. They do aerobics and drink Crystal Light.
As JB would say, “How’s that working for ya?” This week’s study suggests the answer is: Not as well as it could be.
This week I look at a study that reviews a slightly different formula — leg press + milk — and its relationship to women’s weight loss.
Josse AR, Tang JE, Tarnopolsky MA, Phillips SM. Body composition and strength changes in women with milk and resistance exercise. Medicine & Science in Sport & Exercise 42(6):1122-30 (June 2010).
In 2007, these researchers published a study in which men worked out and drink either milk or carbohydrate. Same study, but with women.
The women were recreationally active, but didn’t do any resistance activities (i.e. weight training) for 8 months before the study. This is important: Untrained subjects respond differently than trained subjects (remember this when looking at study results). Participants new to weight training (or returning after a long layoff) will have bigger strength and muscle gains when starting a weight training program than they’d have if they just continued an existing strength training program.
For 12 weeks, the women worked out 5 days a week. Workouts would rotate with push exercise days, pull exercise days and leg exercise days.
Every second week over the 12 week study, the women changed the number of repetitions and sets they performed, and the weights they lifted.
Right after and 1 hour after the workouts, all the women drank 500 mL of a post-workout drink (1 L in total).
- Half the women drank skim milk (fat-free) as their post workout drink
- The other half drank a carbohydrate drink (9% maltodextrin) equal in calories to milk (160 kcal).
Both were flavored with vanilla and the women drank them from an opaque container, so that they wouldn’t know whether they were getting milk or the carb drink.
Before I go on, I should tell you the nutrient breakdown of milk. Milk is primarily a mix of protein (18 g), carbs (25 g), and water. The carbs in milk come from lactose, or milk sugar. So women consuming milk were essentially consuming carbs + protein, while obviously the maltodextrin drinkers were consuming only carbs.
After 12 weeks of working out 5 days a week and drinking their post workout drinks the women lost no weight. In fact, they gained weight.
- The milk group’s average weight went up very slightly (from 72 to 72.5 kg, or 158.7 lb to 159.8 lb)
- The carb group’s average weight went up noticeably (from 68.3 to 69.1 kg, or 150.6 lb to 152.3 lb)
Sounds disastrous, doesn’t it? (Well, at least if you’re the kind of person for whom a 1 or 2 lb gain is “disastrous”.)
If you only look at the scale then yeah, the workouts were useless. But if you look at body composition, then you get a different story.
- The milk drinkers gained 1.9 kg of lean mass (likely muscle, glycogen, and water) while losing 1.6 kg, so on the scale you’d see no difference.
- The carb-only drinkers group gained lean mass too (1.1 kg), but didn’t lose much fat, if any (0.3 kg).
Okay, losing less than 2 kg (5 lb) of fat in 3 months isn’t that great, but this was without any change in diet besides the post-workout drinks. This is another study that supports what JB has been saying in PN newsletters:
Vitamin D deficiency
Yes, vitamin D pops up in yet another study. (See All About Vitamin D for more.)
Women in this study were deficient in vitamin D, as determined by measuring the 25[OH]D (a vitamin D metabolite). And since milk is fortified in vitamin D, women in the milk group had more 25[OH]D in their blood after the study. But even after drinking 1 L of milk five days a week (nearly double the recommended amount of vitamin D), the women in the milk group were still deficient in vitamin D.
Thus, while vitamin D-fortified milk can add to your total D intake, it isn’t necessarily going to give you all that you need.
Both groups had increases in strength (between 45-103%), with only bench press strength being higher in the milk group.
Even though there wasn’t much change in body weight the milk group lost 0.5 kg (just over 1 lb) of fat while gaining lean mass, so there was no difference on the scale. (Yes, this is my not-so-subtle hint that you should quit or at least restrict your scale habit. You know who you are.)
What to do instead of stepping on the scale? In this study the researchers used DEXA to figure out fat loss, but you could use slightly more practical approaches like skinfolds, body circumference/girth measures, and checking how well your clothes fit.
The surprising part to me was the carb group did gain pretty much as the same amount of lean body mass as the muscle group, because you’d think the extra protein from the milk would help build more muscle. Weird. Milk helps with weight loss, but not muscle gains compared to straight carbs.
Vitamin D for fat loss?
How can milk as a post-work out drink lead to more fat lost than a carb post-work out drink?
The researchers think it could be changes in vitamin D metabolism, since milk is fortified with vitamin D. What makes this idea really appealing is that, as I’ve mentioned, the women were deficient in vitamin D (blood 25[OH]D<80 nM). Since the women in the milk group were getting 180% of the recommended vitamin D, you’d think that they would have at least sufficient levels of blood vitamin D, but nope. The milk group did see improvement in blood vitamin D, as I described, but they still didn’t get to sufficient levels in their blood.
Other studies have found that vitamin D levels correlate with body composition.
However I’d like to see a study comparing milk with a protein and carbohydrate post-work out drink before I believe that vitamin D and not protein is the key for fat loss.
Don’t look at the scale when you’re trying to lose weight, because as you lose fat you should gain muscle. The scale won’t move, or worse, it may go in the wrong direction. This can play havoc with your confidence.
Use other methods to judge progress, such as:
- DEXA scan (somewhat less practical for most folks, though)
- Skinfold measurements
- Body circumference/girth measures
- How well your clothes fit
Get more vitamin D.
Milk isn’t a bad post-workout drink compared to just carbs.
Lifting heavy weights can help you lose weight – though not a lot without some sort of significant diet change.
For more on milk, see All About Milk.
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