Higher compared with lower dietary protein during an energy deficit combined with intense exercise promotes greater lean mass gain and fat mass loss: a randomized trial

In the paper

“In subjects who were in energy balance (or mildly positive energy balance), exercise-induced changes in hormones such as testosterone, growth hormone, cortisol, and/or insulin-like growth factor I (IGF-I) were not associated with changes in MPS (10,11), muscle mass (12,13), or strength (13).”

What the sources say

• Partly supported

  The Results report that exercise increased MPS, but MPS did not differ between conditions despite greater hormone elevations in the high-hormone condition. This supports the MPS portion of the citing sentence, to which this source is attached. The paper describes participants as fed and given post-exercise protein; it does not establish that they were in energy balance or mildly positive energy balance. (LLM, conf=0.83)

  cites [10] West, 2009, Resistance exercise-induced increases in putative anabolic hormones do not enhance muscle protein synthesis or intracellular signalling in young men, J Physiol sourceExperimental — accuracy not yet measured
• ?Not checked — no full text of the sourcecites [11] West, 2012, Sex-based comparisons of myofibrillar protein synthesis after resistance exercise in the fed state, J Appl Physiol source
• Partly supported

  The Discussion reports no difference in strength or hypertrophy between arms exposed to low and high postexercise hormone levels after 15 weeks of training. The Results also report elevated cortisol in the high-hormone condition. The cited paper does not establish that participants were in energy balance or mildly positive energy balance; the sentence assigns the MPS finding to other citations. (LLM, conf=0.82)

  cites [12] West, 2010, Elevations in ostensibly anabolic hormones with resistance exercise enhance neither training-induced muscle hypertrophy nor strength of the elbow flexors, J Appl Physiol sourceExperimental — accuracy not yet measured
• Partly supported

  This source is cited for muscle mass and strength, not MPS. The Results report no association between any measured hormone response and leg-press strength, and no association between GH, free testosterone or IGF-1 and lean body mass. But cortisol was positively correlated with gains in lean body mass, while GH and cortisol were correlated with increases in muscle-fibre area, so the blanket claim of no association with muscle mass is not supported. (LLM, conf=0.91)

  cites [13] West, 2012, Associations of exercise-induced hormone profiles and gains in strength and hypertrophy in a large cohort after weight training, Eur J Appl Physiol sourceExperimental — accuracy not yet measured

In the paper

“HIT/SIT also results in rapid gains in aerobic fitness, as well as endurance capacity, thus contributing to physical performance outcomes (8,9).”

What the sources say

• Supported

  Table 1 (Methods, Subjects) shows peak oxygen uptake rising after three and six weeks of SIT, supporting rapid gains in aerobic fitness. The Discussion reports improved volitional exercise performance after six SIT sessions over two weeks, supporting the endurance-performance part of the claim. The latter finding is reported from the authors’ earlier study rather than measured directly in this one. (LLM, conf=0.87)

  cites [8] Burgomaster, 2008, Similar metabolic adaptations during exercise after low volume sprint interval and traditional endurance training in humans, J Physiol source
• Partly supported

  The Results (Indices of cardiometabolic health; page unavailable) report that six weeks of very low-volume SIT increased VO2 peak by 12% and maximal workload by 14%, supporting rapid gains in aerobic fitness and a physical-performance measure. The paper does not report a distinct measure of endurance capacity, so that part of the claim is not established by this study. (LLM, conf=0.85)

  cites [9] Gillen, 2014, Three minutes of all-out intermittent exercise per week increases skeletal muscle oxidative capacity and improves cardiometabolic health, PLoS One sourceExperimental — accuracy not yet measured

In the paper

“Combining a higher protein intake with RT during caloric restriction would act synergistically on the rates of MPS, resulting in a greater ratio of fat to LBM lost during energy restriction (5,6), which may be advantageous for physical performance.”

What the sources say

• ?Not checked — no full text of the sourcecites [5] Mettler, 2010, Increased protein intake reduces lean body mass loss during weight loss in athletes, Med Sci Sports Exerc source
• Partly supported

  The Introduction says that higher protein intake paired with exercise, especially resistance exercise, can work synergistically to maintain lean mass during weight loss. The Discussion reports greater fat loss and lean mass gain with higher protein and dairy intake during energy restriction and combined aerobic and resistance training. Our copy does not establish that this effect operates through synergistic changes in muscle protein synthesis (MPS) rates. (LLM, conf=0.88)

  cites [6] Josse, 2011, Increased consumption of dairy foods and protein during diet- and exercise-induced weight loss promotes fat mass loss and lean mass gain in overweight and obese premenopausal women, J Nutr sourceExperimental — accuracy not yet measured

In the paper

“Current evidence suggests that the energy deficit likely reduces basal MPS (29) and may also have reduced the sensitivity of MPS to feeding (30,31).”

What the sources say

• Supported

  Citation (29) supports the basal MPS clause. The Experimental design section describes fasted, resting measurements, and the FSR results report approximately 19% lower muscle protein synthesis after a 10-day energy deficit than during weight maintenance. The separate claim about sensitivity to feeding is attached to citations (30,31), not this source. (LLM, conf=0.94)

  cites [29] Pasiakos, 2010, Acute energy deprivation affects skeletal muscle protein synthesis and associated intracellular signaling proteins in physically active adults, J Nutr source
• Partly supported

  The Myofibrillar protein synthesis results (page unavailable) report lower postprandial MPS after the 14-day energy deficit, supporting the possibility raised by the citation. But postabsorptive MPS also fell, and the passage does not establish that the feeding-induced increase itself was reduced. The basal-MPS clause is attached to a different citation. (LLM, conf=0.82)

  cites [30] Hector, 2015, von AM, Baker SK, Phillips SM. Whey protein supplementation preserves postprandial myofibrillar protein synthesis during short-term energy restriction in overweight and obese adults, J Nutr sourceExperimental — accuracy not yet measured
• Supported

  The Discussion reports that short-term energy restriction in older men reduced fasted-state MPS, supporting the basal-MPS claim attached to this citation. It also reports reduced fed-state MPS and discusses possible effects on anabolic sensitivity, although the feeding-sensitivity clause is attached to other citations in the citing sentence. (LLM, conf=0.92)

  cites [31] Murphy, 2015, Hypoenergetic diet-induced reductions in myofibrillar protein synthesis are restored with resistance training and balanced daily protein ingestion in older men, Am J Physiol Endocrinol Metab source

In the paper

“We have previously reported a similar pattern of body composition change during a longer-duration intervention in overweight/obese premenopausal women (6).”

What the sources say

• Supported

  The Results (Body composition [DXA]; page unavailable) report fat-mass loss and lean-mass gain in the high-protein, high-dairy group over 16 weeks. The Figure 1 caption identifies the participants as overweight and obese premenopausal women, matching the intervention the citing sentence identifies. (LLM, conf=0.92)

  cites [6] Josse, 2011, Increased consumption of dairy foods and protein during diet- and exercise-induced weight loss promotes fat mass loss and lean mass gain in overweight and obese premenopausal women, J Nutr source

In the paper

“and LBM (r = 20.34,P = 0.03)”

• Also stated in: § RESULTS · plain

  “and LBM (r = 20.34,P = 0.03)”

In the paper

“We observed main effects for time for all hormones and no between-group differences.”

In the paper

“The PRO group had a greater loss of fat mass than did the CON group (PRO: 24.8 6 1.6 kg; CON: 23.5 6 1.4kg; P , 0.05).”

• Also stated in: § RESULTS · plain

  “fat mass losses were greater (P , 0.05) in the PRO group (24.8 6 1.6 kg) than in the CON group (23.5 6 1.4 kg)”

• Also stated in: § DISCUSSION · plain

  “we observed a greater loss (w1.3 kg) of fat mass in the PRO group than in the CON group”

In the paper

“the estimated glomerular filtration rate increased in the PRO group from pre-to postintervention, but remained unchanged in the CON group”

In the paper

“the pooled changes in cortisol could explain only 16% and 11% of the variance in changes in fat mass and LBM, respectively.”

In the paper

“We did not observe any interaction effects between conditions, but did observe main effects over time for all hormones (Table 5).”

In the paper

“LBM remained unchanged in the CON group (0.1 6 1.0 kg; P , 0.45)”

• Also stated in: § DISCUSSION · plain

  “LBM was unchanged during a period of high-intensity exercise training and substantial energy deficit even when the amount of protein consumed (1.2 g $ kg 21 $ d 21 ) was lower”

In the paper

“We observed a significant time-by-condition interaction for blood urea nitrogen, which increased in the PRO group (P , 0.05) and remained unchanged in the CON group”

In the paper

“LBM increased (P , 0.05) in the PRO group (1.2 6 1.0 kg)”

• Also stated in: § RESULTS · plain

  “LBM increased in the PRO group (1.2 6 1.0 kg) compared with preintervention”

• Also stated in: § DISCUSSION · plain

  “higher protein-containing (2.4 g $ kg 21 $ d 21 ) diet consumed during a period of marked energy deficit (w40% reduction in estimated energy requirement) during HIT resulted in an increase in LBM”

In the paper

“and to a greater extent (P , 0.05) compared with the CON group (0.1 6 1.0 kg)”

• Also stated in: § RESULTS · plain

  “this increase was greater (P , 0.05) than in the CON group”

In the paper

“There was substantial weight loss in both groups from pre-to postintervention, but there were no differences in body weight loss between groups (P .0.8)”

In the paper

“Creatinine clearance remained unchanged as a result of the protocol in both groups”

In the paper

“In addition, we did not observe any independent correlations with hormones or any body composition or performance variables (data not shown).”

In the paper

“All measures of exercise performance improved similarly in the PRO and CON groups as a result of the intervention with no effect of protein supplementation.”

• Also stated in: § RESULTS · plain

  “With the exception of isometric knee extension torque, strength increased in all exercises, as did measures of aerobic and anaerobic capacity and performance on sit-up and push-up tests (Table 4).There were no differences between groups for any performance-based variable.”

• Also stated in: § DISCUSSION · plain

  “there were no differential responses in strength, performance, aerobic fitness, or anaerobic power between groups”

In the paper

“Contrary to our findings, these authors (4) reported that a higher protein diet (2.4 g $ kg 21 $ d 21 ) still resulted in a loss of 1.2 6 0.3 kg LBM as a result of the 21-d intervention.”

What the sources say

• ?Not checked — no full text of the sourcecites [4] Pasiakos, 2013, Effects of high-protein diets on fat-free mass and muscle protein synthesis following weight loss: a randomized controlled trial, FASEB J source

In the paper

“In general, cortisol opposes fat loss and promotes loss of LBM during energy restriction (34), which is what we observed.”

In the paper

“Changes in serum cortisol were associated with changes in body fat and LBM, but did not explain much variance in either measure.”

In the paper

“We propose that the disparate findings of the previous study (4) and our findings may be due to the timing of our supplementation and the exercise intensity, which could be important in increasing or maintaining LBM while in a severe energy deficit (3).”

What the sources say

• ?Not checked — no full text of the sourcecites [4] Pasiakos, 2013, Effects of high-protein diets on fat-free mass and muscle protein synthesis following weight loss: a randomized controlled trial, FASEB J source
• ?Not checked — no full text of the sourcecites [3] Areta, 2014, Reduced resting skeletal muscle protein synthesis is rescued by resistance exercise and protein ingestion following short-term energy deficit, Am J Physiol Endocrinol Metab source

In the paper

“As an objective measure of compliance with the PRO diet, we measured serum urea and noted that it increased during the intervention and remained unchanged in the CON group.”

In the paper

“however, when under extreme energy deprivation combined with high energy expenditure, there have been associations observed between changes in hormones and body composition (15,16).”

What the sources say

• ?Not checked — no full text of the sourcecites [15] Alemany, 2008, Effects of dietary protein content on IGF-I, testosterone, and body composition during 8 days of severe energy deficit and arduous physical activity, J Appl Physiol source
• ?Not checked — no full text of the sourcecites [16] Nindl, 2007, Utility of circulating IGF-I as a biomarker for assessing body composition changes in men during periods of high physical activity superimposed upon energy and sleep restriction, J Appl Physiol source

In the paper

“Other research suggests that $2 g protein $ kg 21 $ d 21 may be required to maintain LBM when an individual is in an energy deficit (5).”

What the sources say

• ?Not checked — no full text of the sourcecites [5] Mettler, 2010, Increased protein intake reduces lean body mass loss during weight loss in athletes, Med Sci Sports Exerc source

In the paper

“This trial was registered at clinicaltrials.govas NCT01776359.”

• Also stated in: § Research participants · plain

  “(NCT01776359)”

In the paper

“Compliance with the nutritional intervention (i.e., consumption of all the provided study foods) was assessed by daily contact with participants, food consumption checklists, and daily weight monitoring, and was estimated to be 93%.”

In the paper

“Because of the nature of the trial, it was impractical to maintain a double-blinded scheme, and yet we do not think this influenced the outcomes, because all analyses were done in a blinded manner and data were only unblinded after all analyses were complete.”

In the paper

“Evidence from Areta et al. (3) showed that consuming 30 g protein after resistance exercise while in an energy deficit resulted in a greater stimulation of muscle protein synthesis (MPS) than did consumption of 15 g protein.”

What the sources say

• ?Not checked — no full text of the sourcecites [3] Areta, 2014, Reduced resting skeletal muscle protein synthesis is rescued by resistance exercise and protein ingestion following short-term energy deficit, Am J Physiol Endocrinol Metab source

In the paper

“A potential limitation of the present trial is the free-living nature of the protocol.”

In the paper

“Data from Trapp et al. (25) suggest that lipolysis increases over 20 min of HIT training gradually with each session.”

What the sources say

• ?Not checked — no full text of the sourcecites Trapp et al. [25] Trapp, 2008, The effects of high-intensity intermittent exercise training on fat loss and fasting insulin levels of young women, Int J Obes (Lond) source

In the paper

“In conclusion, the current study provides direct evidence that a higher protein diet during substantial energy deficit and HIT not only preserves, but increases, LBM and HIT during the energy deficit, irrespective of protein intake, and increases strength and performance in young men.”

In the paper

“Hypoenergetic diet-induced weight loss results in w20-30% of mass lost as lean body mass (LBM), 3 with the remaining mass lost from adipose tissue (1).”

What the sources say

• ?Not checked — no full text of the sourcecites [1] Weinheimer, 2010, A systematic review of the separate and combined effects of energy restriction and exercise on fat-free mass in middle-aged and older adults: implications for sarcopenic obesity, Nutr Rev source

In the paper

“In general, cortisol opposes fat loss and promotes loss of LBM during energy restriction (34), which is what we observed.”

What the sources say

• ?Not checked — no full text of the sourcecites [34] Seimon, 2013, Effects of energy restriction on activity of the hypothalamo-pituitary-adrenal axis in obese humans and rodents: implications for diet-induced changes in body composition, Horm Mol Biol Clin Investig source

In the paper

“Pasiakos et al. (4) reported that daily protein at twice the Recommended Dietary Allowance (RDA) for protein attenuated the loss of LBM during an energy deficit with both aerobic and resistance exercise.”

What the sources say

• ?Not checked — no full text of the sourcecites [4] Pasiakos, 2013, Effects of high-protein diets on fat-free mass and muscle protein synthesis following weight loss: a randomized controlled trial, FASEB J source

In the paper

“Intra-and interassay CVs for these metabolites were all ,5%.”

In the paper

“We had good compliance with exercise intervention and propose that subjects exerted high degrees of effort when requested.”

In the paper

“All data were analyzed with the use of a 2-factor repeated measures ANCOVA with protein intake (between) and time (within) as the main variables.Covariates included age, height, weight, baseline body composition (when assessing body composition), and baseline performance measures (when assessing changes in performance).”

In the paper

“Sample sizes were determined a priori powered on the primary outcome of lean mass loss (by dual-energy X-ray absorptiometry) to detect a differential lean mass loss of 1 kg, with a = 0.05 and power at 90%, to require 16 subjects/group”

In the paper

“All intra-and interassay CVs for these hormones were ,8%, with the exception of free testosterone, which was ,11%.”

In the paper

“Our hormonal data align roughly with previous work in military personnel undergoing high levels of daily activity in an extreme energy deficit (15,16).”

What the sources say

• ?Not checked — no full text of the sourcecites [15] Alemany, 2008, Effects of dietary protein content on IGF-I, testosterone, and body composition during 8 days of severe energy deficit and arduous physical activity, J Appl Physiol source
• ?Not checked — no full text of the sourcecites [16] Nindl, 2007, Utility of circulating IGF-I as a biomarker for assessing body composition changes in men during periods of high physical activity superimposed upon energy and sleep restriction, J Appl Physiol source

In the paper

“Body composition was determined with the use of a 4compartment model of body composition as described previously (19).”

• Also stated in: § Body composition · plain

  “CVs for repeated measures on subsequent days were the following: BodPod, 1.2%; bioelectrical impendance, 1.9%; and dual-energy X-ray absorptiometry, 0.8%.”

What the sources say

• ?Not checked — no full text of the sourcecites [19] Wilson, 2013, Improved 4-compartment body-composition model for a clinically accessible measure of total body protein, Am J Clin Nutr source

In the paper

“The percentage change in free IGF-I was, in the previous work (16), shown to be correlated with the percentage change in fat mass;”

What the sources say

• ?Not checked — no full text of the sourcecites [16] Nindl, 2007, Utility of circulating IGF-I as a biomarker for assessing body composition changes in men during periods of high physical activity superimposed upon energy and sleep restriction, J Appl Physiol source

In the paper

“Because of the nature of the trial, it was impractical to maintain a double-blinded scheme, and yet we do not think this influenced the outcomes, because all analyses were done in a blinded manner and data were only unblinded after all analyses were complete.”

In the paper

“The trial protocol was approved by the Hamilton Integrated Research Ethics Board and complied with the standards as set out in the Canadian Tri-Council Policy statement on the use of human participants in research”

In the paper

“In the study described in these publications (15,16), the degree of energy deficit was greater and protein intake was much lower than in the present study.”

What the sources say

• ?Not checked — no full text of the sourcecites [15] Alemany, 2008, Effects of dietary protein content on IGF-I, testosterone, and body composition during 8 days of severe energy deficit and arduous physical activity, J Appl Physiol source
• ?Not checked — no full text of the sourcecites [16] Nindl, 2007, Utility of circulating IGF-I as a biomarker for assessing body composition changes in men during periods of high physical activity superimposed upon energy and sleep restriction, J Appl Physiol source

In the paper

“RT attenuates the loss of skeletal muscle mass during an energy deficit presumably by stimulating MPS (3,4).”

What the sources say

• ?Not checked — no full text of the sourcecites [3] Areta, 2014, Reduced resting skeletal muscle protein synthesis is rescued by resistance exercise and protein ingestion following short-term energy deficit, Am J Physiol Endocrinol Metab source
• ?Not checked — no full text of the sourcecites [4] Pasiakos, 2013, Effects of high-protein diets on fat-free mass and muscle protein synthesis following weight loss: a randomized controlled trial, FASEB J source

In the paper

“We had good compliance with exercise intervention and propose that subjects exerted high degrees of effort when requested.”

In the paper

“participants were randomly assigned (with the use of the random number generation of a code: http://www.randomization.com/)”

In the paper

“We used a single-blind, randomized, parallel-group prospective trial.”

• Also stated in: § Research participants · plain

  “The trial was a single-blind, randomized, parallel prospective trial conducted between January 2013 and February 2014 (NCT01776359) at McMaster University.”

In the paper

“These authors (4) included groups that consumed protein at 3 levels-0.8,1.6, and 2.4 g $ kg 21 $ d 21 -and reported a substantial retention of LBM for the 1.6 g $ kg 21 $ d 21 group, but not with consumption of 2.4 g $ kg 21 $ d 21 of protein.”

What the sources say

• ?Not checked — no full text of the sourcecites [4] Pasiakos, 2013, Effects of high-protein diets on fat-free mass and muscle protein synthesis following weight loss: a randomized controlled trial, FASEB J source

In the paper

“This research suggests that the high-intensity exercise our current participants were subjected to likely enhanced their capacity for fat oxidation and may have induced an increase in muscle mitochondrial enzyme activity (25).”

What the sources say

• ?Not checked — no full text of the sourcecites [25] Trapp, 2008, The effects of high-intensity intermittent exercise training on fat loss and fasting insulin levels of young women, Int J Obes (Lond) source

In the paper

“Nonetheless, we are unaware of data that would suggest that a greater or lesser fat intake, at least of the magnitude seen here, would promote differential lean mass retention and/or differential fat loss when the energy deficit is identical.”

In the paper

“Our data suggest that during a substantial energy deficit, higher protein consumption (2.4 g $ kg 21 $ d 21 ) resulted in an increased stimulation of MPS and/or a suppression of proteolysis to a greater extent than consumption of 1.2 g $ kg 21 $ d 21 , as evidenced by gains in LBM in the PRO group.”