What happens when dieting, cardio, and lifting go head-to-head for body recomposition?
The Origin Story…
All over the interwebs are blogs and articles discussing what avenue toward weight loss is better for women. Should they just diet their way to skinny? Should they lean out through exercise? Cardio? Weight lifting?
Well, as I always do, I have a study today that approached these questions…just in time for our end of the year holiday-gain-train-extravaganza! The 1997 paper is titled, Physiological adaptations to a weight-loss dietary regimen and exercise programs in women. It’s brought to us by Kraemer, et al.
This study lasted 12 transformation-sensation weeks and had all female participants. There were 4 groups. The first was the control group, who did nothing for the 12 weeks. The second group did only a diet for 12 weeks. They met with the researchers once a week for counseling and maintained a food diary. The third group did the same diet program, and also did cardio sessions for 50 minutes, 3 days a week, with the researchers. The cardio sessions involved a variety of exercises with a target heart rate of 70-80% max heart rate. The fourth group did the same diet program, and also did a combined cardio and weight lifting session 3 days a week with the researchers. The weight lifters had a solid barbell/dumbbell program. There were 11 exercises, ranging from bench presses to rows. For session 1 of each week, the lifters did 3 sets of 5-7RM for each lift. For session 2 each week, the lifters did 3 sets of 8-10RM for each lift.
Below are the starting descriptive stats of each group. As always, they’re group averages and rounded to the nearest whole number for the ease of viewing.
All of the participants were sedentary, overweight, and had physicals to ensure that they were healthy enough to complete the study. They had pre/post measurements taken of their scale weight, body fat level, 1RM strength, VO2max, resting metabolic rate (RMR), and blood work.
Let’s state outright what everyone wants to know. How much weight did each group lose in 12 weeks? The control group did not lose any weight. The diet-only group lost an average of 14 lbs. The cardio and diet group lost 15 lbs, on average. The cardio, weight lifting, and diet group lost 15 lbs also, on average. Yes, that’s right. All 3 experimental groups lost basically the same weight.
The experimental participants lost just over 1 lb a week, which with their food diaries put them at an estimated average 1200 kcals/day over the 12 weeks.
There was a decrease in the average RMRs for all 3 experimental groups. The decreases ranged from 30 to 143 kcals. When the researchers looked at the changes in RMR based on the lb-for-lb body weight of the participants, they found that there was no relative change. At the end of the study, the range of the RMRs was 1327-1487 kcals/day for the 3 groups.
These researchers were kind enough to break out the participants into individual data points when they examined the RMRs as related to LBM. Most studies publish the group data as averages and we do not get to see the individual differences and variability. In this case, we get to see them. Below are figures 2A-C, directly from the paper. The x-axis is the LBM (in kg) and the y-axis is the RMR/day. Open circles are the initial measurements and solid circles are the final measurements. 2A is the diet-only group, 2B is the diet/cardio group, and 2C is the diet/cardio/weights group.
Implications / Thoughts
One of the benefits of examining the individual weight and RMR is that we get to see the variation in the population. I will raise this point again in future journal clubs. There are 3 participants in figure 2A that have roughly the same RMR (~1500-1600) while their LBM varies by as much as 22 lbs. That is an example of 3 differently sized people who could very easily claim they have different (resting) metabolisms…but actually don’t. On the flip side, figure 2C shows 3 participants with roughly the same LBM (~94 lbs) and different RMRs (1000-1350 kcals). That is an example of a group that should not have a weight-loss competition. The one burning 1350 kcals/day would have an advantage against the one burning 1000 kcals/day. This variability is why I think that we must actually get our RMRs measured before we can make any claims. We can get results without measuring our RMRs, but I am not a fan of making claims about how high or low our RMRs are if we have not empirically measured them. We cannot rely on interweb prediction equations (as the last paper showed).
I have a thought about why all 3 of these groups lost the same amount of weight. When the researchers were counseling the participants, they set 1 lb a week as the target weight loss rate. I think, perhaps the exercisers took that target to heart and adjusted their diet adherence accordingly. When they hit that 1 lb lost in a week, they likely thought that they had few enough kcals. In reality, they were eating more kcals than the diet-only group and the energy deficit they experienced was partially created by their exercising. The existence of an energy deficit is a function of our total daily energy expenditure (TDEE), not just our RMR.
To be continued…
You may be thinking to yourself, what about the LBM, the strength, and the blood work results?! Well, my friends, that is going to be covered in part deux. Further, I will bring all of these components of the study together and explain what I think all of it means for us. Check back next week for part deux!
If you have any questions about this study or anything I said, please feel free to leave a comment. I will get back to you and others may have insight to offer, too. If you have any questions or topic suggestions that you would like answered as a post, then please email me at email@example.com.
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