Women in Their 30s who 'Hit the Weights' While Dieting Get Toned = 2lbs of Fat Loss for Each 1lbs of Muscle They Gain

Shape's "fat loss" variety of the FITT workout still focuses on cardio.
This article is about a paper by Miller et al. (2017) that is going to be published in one of the next issues of the International Journal of Sport Nutrition and Exercise Metabolism. The study itself is thus clearly 'news'. What's not news, however, is the message that women benefit (just as much if not more) from lifting weights while dieting as men.

Unfortunately, the message is rarely heard and often ignored. Obviously, the lure of the calorie counters on the treadmills and crosstrainers of this world is too strong for the average diet-willing female human being to resist trampling along on the crosstrainer to burn 500kcal and thus afford/make good for "that pizza" ("Never Train to Burn Calories").
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Miller, Mull, Aragon, Krieger and Schoenfeld (re-)addressed three issues related to exercise- / diet- / exercise+diet-driven, improvements in body composition, improvements in visceral fat mass, and changes in muscle mass in a caloric deficit.

To this end, a convenience sample of 40 female overweight/obese volunteers (Body mass = 87.4±12.6; Height = 165.7±7; Age = 32.3±4.8; BMI = 31.9±4.4). The sample size was based on previous research achieving a target effect size difference of 0.4, alpha of 0.05 and minimum power of 0.80. Only women with a regular menstrual cycle, more than 30% body fat, normal activity levels below the CDC recommendations, and no organized weight training within the last year who hadn't been dieting or food logging when the study began. In other words: The study's subjects may be overweight, but they are healthy, young and representative of an expanding part of today's female population.

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That's yet not the only thing that makes this study stick out (in a positive way). There are also (i) the previously cited three-tier research question that (a) doesn't falsely focus on weight loss and (b) addresses the important issue of lean mass losses while dieting, and (ii) the accuracy of the tools the authors used to assess the subjects' body comp (Dual Energy X-ray Absorptiometry | DXA) and resting metabolic rate (RMR | indirect calorimetry). Obviously, even those are not infallible, either, they are more reliable than measuring body comp. w/ BIA (impedance analysis ~ more expensive version of your bodyfat-scale) and calculating the resting metabolic rate using exclusively (cf. diet info) generic formula that was designed for Mrs. Average on an energy-sufficient diet.
How did the scientists determine the Ladies' total energy requirements: While Miller et al. had indirect calorimetry data, a registered dietician compared the measured to calculated (Harris-Benedict) RMRs for all women and added or subtracted 10% off the measured RMR for all women, where the measured RMR was not within 10% of the predicted RMR. It is important to understand that this is different from simply taking the calculated RMR. The latter could (and probably was) easily be 25% off and still, only the standard margin of error of 10% would be added to the experimentally established RMR (not the 25% which would mean taking the calculated RMR).
Where the study did not differ from the average, though, is in terms of its use of a standardized randomization process to assign the 40 ladies to one of the following four treatment groups:
  • The RT intervention consisted of two separate workout complexes that were alternated every 4 weeks for the duration of the 16-week study. Exercise complex one consisted of Squats, Romanian Deadlifts, Swiss Ball Squats, Bench Press, Lat Pulldown, Dumbbell Shoulder Press, Incline Dumbbell Fly, Seated Row, Dumbbell Lateral Raise and Low Back Hyperextensions. Exercise complex two consisted of Deadlifts, Leg Curls, Leg Extensions, Incline Dumbbell Press, Close Grip Pull-downs, Arnold Press, Cable Cross-over, Chest Supported Dumbbell Row, Face Pulls and Low Back Hyperextension. Each exercise was completed for 4 sets of 10-12RM (weight was increased if 4 sets of 12 could be done). Rest periods between sets were between 60-90 seconds. Subjects trained 3 times per week for weeks 1- 3 of each month, then trained twice weekly during the 4th week of each month.
    Dietary intervention only (DIET n=10) - received daily macronutrient and calorie goals based on their DXA and RMR tests from a registered diet (more the way the energy requirements were determined in the box above this paragraph); protein intake was calculated using factor of 3.1 g of protein per kg of fat-free mass; fat intake was set at 20% of total calories; carbohydrate made up the balance of the remaining calories
  • Resistance Training only (RT n=10) - after having been familiarized with all exercises and establishing appropriate training loads, all subjects performed 2-3 training sessions (two separate workout complexes that were alternated every 4 weeks for the duration of the 16-week study) under the individual supervision of a certified personal trainer for 16 weeks details to the right of this paragraph)
  • Resistance Training plus Diet (RT+DIET n=10) - did both, what's described for the DIET and the RT group and thus combined, as the name implies, resistance training plus diet
To ensure dietary compliance, the women in the DIET and RT+DIET groups met regularly with their dietitian and tracked their food consumption using a combination of phone app/website (fatsecret.com). 
Figure 1: Actual macronutrient intakes in DIET (blue) and DIET+RT (orange) groups in grams or %-ages (Miller 2017).
The data were analyzed using a linear mixed model for repeated measures, estimated by a restricted maximum likelihood algorithm, with drop-outs removed from the dataset (subject individuality was included as a random effect). Secondary analyses (e.g. subgroup) in form of linear time trends were conducted and analyzed using linear mixed models for repeated measures if significant interactions were found for intervention, months/duration or both month x intervention.

And here's what the study found

A total of 31 subjects completed the study, with 9 dropouts  and no inter-group differences (Control: n=8; RT: n=9; DIET: n=9; RT+DIET: n=5). In absolutes, the ladies in the RT+DIET group, of whom you could argue that they had the 'hardest job', had lowest dropout rate. In view of the fact that we don't know the individual reasons for quitting for 5 subjects and the other reasons were not intervention related, it is yet unwarranted to speculate that this may be because the women in the RT+DIET group saw the greatest success. However, those women who did both, resistance training and dieting, simply did see the greatest success.
  • baseline: subjects in all groups started with (within expected statistical margins) identical body composition (BMI, fat/lean mass), bone mineral contents (BMR), and resting metabolic rates (RMR)
  • Figure 2: When looking at the changes on a regular scale more is not necessarily bad; after all, getting 'toned' is all about body composition, not weight (Miller 2017);  **denotes significant pre-post increases
    diet/deficit: the macronutrient intakes of the DIET and DIET+RT group didn't differ significantly; according to their food logs, the DIET group did yet achieve a smaller (~502 kcal/day) energy deficit than the RT+DIET (~632 kcal/d) group; worth mentioning, the DIET group reduced their fat intake significantly (β = -1.20) while the DIET+RT group kept eating as much fat as they did at baseline - in view of the fact that the intakes didn't differ though, it would be haphazard to use this difference as evidence in favor of the often-praised (but scientifically still unproven) of eating fat for anyone striving to shed body fat
  • BMI: in view of the small difference between the energy deficits of the DIET and DIET+RT group, it is hardly surprising that the reductions in BMI were identical for both groups
Now, that we've passed by the rather boring topics, let's finally get to the changes of which I know that they will interest you most: body fat %, total body fat and lean mass changes...
  • body fat % (relative): in contrast to what Miller et al. observed for the bodyweight-based BMI, though, there was a statistically significant time x treatment effect for the subjects' body fat %: while the control group didn't lose weight, all three treatment groups reduced their body fat % significantly; the inter-group differences of the linear regression coefficients (β=-0.4; β=-0.57; β=-0.53 for DIET, RT and RT+DIET) didn't reach statistical significance but suggests an equal efficacy of DIET and RT and a slightly faster pace of body fat (total) reduction in the RT+DIET group
    Figure 3: Changes in fat mass (top) and lean mass (both), both values are expressed relative to baseline total fat mass and lean mass in kg; for the fat loss of the DIET+RT group that's 3.3 kg fat lost (Miller 2017).
    Note: To calculate the change for lean mass in DIET+RTI used the 3-months data-point because the lean mass dropped back to baseline in month 4 - Typo? Anyway, the lean mass has previously been increasing linearly, which would support the notion that there was no sudden loss of lean mass in the 4th month of the study period.
  • body fat (absolute): a similar trend was observed for the amount of total body fat, which was reduced in all treatment groups with the RT (β = -0.58) group having the smallest slope (=slowest fat loss) and the RT+DIET group (β = -1.80) having the steepest slope (=fastest fat loss | DIET w/  β = -1.35 was in-between); the t-test for multiple comparisons shows that even here, only the difference between the RT (only) and the RT+DIET group was statistically significant
  • lean mass: while the control, and the DIET and RT+DIET group didn't gain significant amounts of lean mass the authors observed a significant linear increase in the resistance training-only (β = 0.76) group - if we discard their statistical nature and take the calculated coefficients from the linear analyses of the body fat and lean mass changes at face value, the DIET+RT group did thus gain more than 1lbs of muscle for every to 2 lbs of fat they lost - impressive!
The bone mineral density and the subjects' amount of visceral adipose tissue didn't change in any group. Interestingly, the same can be said of the RMR - DIET (only) did thus not lead to the falsely dreaded scientifically non-existent 'metabolic damage', in other words:

No, dieting does not reduce your resting metabolic rate, let alone damage your metabolism

Ok, over a study period of 16 weeks and with a deficit of only 500kcal that wasn't very likely, anyway. In view of the fact that there are still people out there who tell their clients that they have to eat more (and I'm not talking about exchanging foods with high- with foods w/ low-energy density, here) to start losing fat, I thought it may protect some of the readers from wasting their money on dietary advice that's not just useless, but downright counter-productive (for 99% of the trainees; esp. females)...

...by the way, doing things wrong somehow reminds me of this one: Only recently a study in women with PCOS showed that the "magic macros" everyone seems to be looking for, these days, may be less important than the actual foods you eat. Missed that study? Update your nutrition knowledge!
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Bottom line: Listen, ladies, don't run away! That the headline says that you will gain muscle if you combine DIET + RESISTANCE TRAINING is GOOD NEWS!

Yeah, the absolutely small increase in lean mass are good news, 'cause that's the way to get 'toned'. Yes, that's right, starving yourself with deficits way beyond 20-30% for months and doing an hour of steady-state cardio every or at least every other day will only have you shrivel - which is, let's be honest, much worse than being ~30% body fat, no?

What? Oh, yes, you could have known that before, but the study at hand is IMHO one of the methodologically most solid (study design, control, stat. analyses, etc.) examinations of the individual and differential effects of diet and resistance training on the body composition of a sufficiently large group of women, who are younger (30-40), and healthy - that sounds pretty much the audience of magazines like "SHAPE" (surprisingly, the avg. age of the shape reader is 44.5y and thus higher than in the study at hand, though | GfK 2016) | Comment!
  • Miller, Todd, et al. "Resistance Training Combined With Diet Decreases Body Fat While Preserving Lean Mass Independent of Resting Metabolic Rate: A Randomized Trial." International Journal of Sport Nutrition and Exercise Metabolism (2017): 1-24.
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