Sex, HIIT & Perceived Readiness: Any News on the Optimal Rest Times for Self-Paced HIIT Regimen in Men & Women?

Surrender bro, women are tougher than we'll ever be... and let's not talk about the other tactics by the means of which they trick us into doing whatever they want without us even noticing :-o

In the world of search engines for scientific papers on training and exercise science the acronym "HIIT" is currently what the word "sex" has always been on Google & co. Against that background it is actually surprising that no one else but me has taken notice of a paper on the "Sex specific  responses  to  self-paced,  high-intensity  interval  training  with  variable  recovery periods". The corresponding research was conducted by C. Matthew Laurent et al. from the School of Human Movement, Sport and Leisure Studies at the Bowling Green State University in Ohio and the paper is about to be published in an upcoming issue of the Journal of Strength and Conditioning Research (Laurent. 2013)

Men are different, women too

The results of previous experiments suggest that women are tougher than men, when it comes to steady state high intensity exercise at a self-selected pace. In their most recent study that involved 16 subjects (8 men and 8 women) between 19 and 30 years of age who had been participating in at least one session of interval training per week within the past months, Laurent et al. set out to test whether this would apply to HIIT sessions with fixed rest periods, but also variable, self-selected intensities. To this end, they had their subjects perform three bouts of HIIT.

"Each session consisted of 6, 4-minute intervals interspersed with either 1, 2, or 4 minutes of recovery. The recovery duration was counterbalanced and subjects  were  informed  of  the  specific  work-to-rest ratio  prior  to  performing  each  session.   Each  trial began  with  a  5-minute  warm-up  that  consisted  of  walking  4.8  km/h at  5%  incline." 

Suggested read: "8x Increase in PGC1-Alpha Cycling in Glycogen Depleted State" (read more)

The subjects were told to set the treadmill to the highest possible speed they felt they could maintain for 4 minutes knowing they were to perform 6 intervals.

The treadmill remained elevated at 5% incline for the duration of the whole session. Prior to each interval, subjects estimated their level of readiness using a perceived readiness scale.

Throughout and at the end of each interval, VO2(ml/kg/min), heart rate (bpm), and rate of perceived exertion (RPE) were measured, recorded and statistically processed.

At the conclusion of the fourth minute, the treadmill was slowed to 4.8 km/h for an active recovery.

"These procedures were followed identically for each of the 6 intervals and across all 3 trials. At the conclusion of the final interval of each session, subjects were disconnected from the metabolic system and sat quietly in a chair in the laboratory for approximately 15-20 minutes whereupon they provided a session RPE (SRPE) using the OMNI scale. "

All subjects were given at least 72 hours but no more than 10 days of rest between HIIT sessions, at the end of which the scientists had made the following observations:

• 

  Triple your energy expenditure by doing shorter shuttle runs (learn more)

  Men ran at significantly higher relative velocities (i.e., %VO2peak) during the  1-minute  recovery  trial  with  the  effect size suggesting a large difference.
• The same velocity and effect size advantage for the strong sex was evident during the trial with 2 min rest times, as well, but in this case the difference was no longer significant.
• Even during the 4-minute recovery trial, men ran at higher velocities but the values were not significantly different and the effect size was considerably low.

Interestingly the women still had the higher %VO2 peak values during all conditions - in other words, relative to their physical constitution, they were performing at a higher intensity than the men irrespective of the fact the latter were running faster. Interestingly the difference was only significant during the 4-min rest condition (if you look at the data in figure 1 you will realize they had to pay for that dearly).

"Apropos active rest - what's the best?"
If you take a closer look at the data in figure 1, you will realize that the 4-min-condition with a work-to-rest ratio of 4:2 (in other words, the 2min rest-condition) appears to have a slight advantage over the other conditions. While the VO2 max may be ~1% higher in the short rest condition (VO2 data not shown), this is not worth the increased exertion both men and women experienced when they ran their 4-min intervals with only 1min of active rest in-between.

Figure 1: Lactate levels, perceived readiness before the HIIT bout, rate of perceived exertion right after and 15min the self-paced HIIT bout with 1, 2 and 4min active rest between sets in male and female subjects; all data expressed relative to the mean value for the respective parameter, data calculated for men and women separately (Laurent. 2013)

As far as the 4:4 condition is concerned it is certainly remarkable that the female participants appear to totally exhaust themselves during that condition. It is difficult to determine, whether this is a result of "getting out of the groove" due to the long rest period (if you are jogging you may know that once you stop for more than a minute it's very difficult to get into the groove again), or whether that may be a result of the fact that they were pushing themselves harder when they knew there would be a long recovery period. Personally I tend to believe that it's the latter effect. Otherwise, the male participants of the study at hand should have experienced a similar negative effect of resting too long. Now, whether that's a sign of toughness or rather one of hubris is a question I'd rather not answer ;-)

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(Re)read the SuppVersity HIIT Series and learn about the optimal interval:rest ratios for your personal training goals (click here)

Bottom line: Whether you can truly argue, that 4:2 is the optimal ratio is at least in my humble opinion still open - regardless of your sex by the way. So, if you are not sure what to do, try a couple of different interval:rest ratios and see how you feel. Meanwhile, I'd suggest you remember that the word "training" comes from "to train" and refers to the "sustained practice [...] in an art, profession, occupation, or procedure, with a view to proficiency in it" (Oxford English Dictionary). Proficiency in this context means that you achieve performance increases and those are not a necessary (and in most cases not even a likely) consequence of feeling like you have been run over by a train.

Once you've figured out what works best for you, stick to it! I don't care if it's 2:1 or 30s:1min, as long as it works for you and you don't have to drag yourself to the track or the gym, whenever your HIIT sessions are due, that's your personal optimum. You should still keep in mind that this optimum may change with your current performance / weight loss / hypertrophy goals and the corresponding amount of energy you consume. Previous research, for example, suggests that long(er) intervals (in the 4min range) could have a slight edge over very short ultra-intense ones, especially when your primary goal is to shed body fat (learn more in the HIIT Special Part I & Part II)

References: 

• Laurent CM, Vervaecke LS, Kutz MR, Green JM. Sex specific responses to self-paced, high-intensity interval training with variable recovery periods. J Strength Cond Res. 2013 Jul 8. [Epub ahead of print]

Strength Training Ain't For Women, One Set is Not Enough and Without a 100% Dialed in Diet Lifting Weights is Useless, Anyways - Really!?

Image 1: Minimalist strength training for maximal results? In the long run even a one set strength circuit can elicit astonishing changes, if you train consistently, progressively, heavy and with picture perfect form (image Paramount Fitness).

Unconventional wisdom days at the SuppVersity: After yesterdays "news" (I hope it was not real news for the majority of you) about the superiority of high intensity interval over classic steady state cardio in at the lower end of the "fat burning zone", today's news is going to cause a couple of other set-in stone paradigms to totter:

1. resistance training ain't for women
2. low volume resistance training won't help you lose body fat
3. resistance training requires a high protein diet to work

The respective data comes from a recently published study by R. Washburn and his colleagues from the Center for Physical Activity and Weight Management at the University of Kansas and researchers from the Southern Illinois University and the Birgham Young University (Washburn. 2012).

Minimal effort, maximal adherence, ...

In their 6-month intervention trial, Washburn and his colleagues set out to evaluate the effect of a minimalist resistance training routine consisting of no more than a single set of 9 different exercises that had to performed three times per week. The sessions were supervised and the participants, overweight young men and women in their early twenties (BMI 27.2kg/m²; age 20.7y; BF% by DEXA 27.6% men, 38.9% women) performed all their exercises on standard gym equipment (Paramount Fitness, not a sponsor of the study!); an adherence of >90% was required and the supervisors made sure that all exercises were performed in the prescribed 3-6RM (85% of 1RM) with a cadence of 2s for the concentric and 4s for the eccentric period of each exercise with picture perfect form:

Tip for advanced beginners You are already training for 4-6 months? Why don't you add in a 2nd circle, 1s concentric, 2-3s eccentric, in the 8-12 rep range. I don't need a scientific study to confirm that this will be able to propel your gains. And with a couple of tweaks to your diet, e.g. 20g of quality protein with every meal and a reduced carbohydrate intake (~25-35% of total energy or 120-250g of carbs) from whole food sources, only, it won't take too long very long to see visible results.
• chest press,
• back extensions,
• lat pull down,
• triceps extensions,
• shoulder press, 
• leg press, 
• calf raise,
• leg curl,
• crunch

Whenever subjects were able to perform more than the required 6 repetitions with good form the resistance was increased by ~2.25kg. In other words the participants followed a stupidly simple linear progression protocol with a clear focus on strength, an ultra-low volume (per muscle group) and picture perfect form.

... results despite unaltered and obviously obesogenic eating habits

Dietary intake before and during the 6-month study period was assessed, I quote, "during one randomly selected period" each month (24hr food recalls on 2 weekdays and one day on the weekend, each) and remained at ~2300kcal. The majority of the daily energy intake came from carbohydrates (51% ~290g) and fats (33% ~95g), while the protein intake (16% ~92g) despite being at the upper level of the RDA would be considered "borderline deficient" from the perspective of most strength trainees.
Note: It stands to reason that a higher protein intake of ~120g+ could have had beneficial effects on strength gains and changes in body composition. Notwithstanding, the results of this study do confirm that not everything that has been shown to facilitate gains is actually necessary and protein intakes in the >3g/kg body weight range, despite not being as bad for your health as the medical orthodoxy would have it, will offer little to no marginal utility and may even turn against you, when you keep upping your protein intake at the expense of more readily available energy sources such as carbohydrates and fats so that the lion's share of your energy has to be derived from dietary protein via glyconeogenesis... add an energetically demanding training program on top of this, call it either adrenal fatigue or central fatigue syndrome and join the other obstinate whiners on the various overtraining, ah... I mean fitness and bodybuilding boards on the Internet.
Without any cardiovascular training, not a single change in their obviously unhealthy dietary habits (why else would these young men and women have become overweight in the first place?) the 37 formerly sedentary twens in the resistance training (RT) training arm of the study derived non-negligible benefits from their weekly workouts:

Figure 1: Changes in BMI, fat free mass (FFM) and fat mass (FM) in male and female study participants in the control and resistance training arm of the 6-months exercise-only single-set circuit training (9 exercises total, 3 training sessions per week) intervention (data based on Washburn. 2012)

I mean, as disappointing as the non-existent weight loss may seem in a society, where the majority of people is so fixated on nondescript figures on a scale, you can hardly argue that

• increasing your muscle mass by +1.5kg,
• decreasing your fat mass (women), or at least 
• ameliorating your fat gains (men) 

would not be better than losing muscle and becoming fatter and fatter as it happened to the subjects in the control arm, right? And that the anti-obesity (as defined by too much body fat, not too much body weight) effects were more pronounced in the 15 women than in their male peers goes to show you that exactly those people (=women ;-) who usually don't lift weights will benefit most from hopping of their steppers, treadmills and recumbent bikes three times a week to do nothing but a single full-body strength circuit.

Training is a nutrient repartitioner, but if the diet does not deliver those the results are suboptimal

These unquestionably favorable (compared to the sedentary control), yet hardly earth shattering results would certainly have been way more impressive, if the study participants had made appropriate changes to their diets. For most of them, it would probably have been enough to simply switch from fast-, fried- away-from-home- and ready-made foods to self-prepared meals, to double, if not triple their results (cf. Taveras. 2005; Wosje. 2010; see also red box below). With the aforementioned tip to get at least 20g of lean protein with every meal and a progression not just on the weight, but also on the volume side of things (yet to no more than 2-3 circles per training, cf. Van Etten, 1997; Shaibi. 2006; Shaw. 2006), the same simplistic full-body circuit would certainly have had a much greater impact on the chubby physiques of the soon-to-be obese type II diabetics.
Food quality? It is quite interesting that both Taveras and Wosje identify fried foods as especially problematic for children and adolescents (Taveras. 2005; Wosje. 2010). And while those were related to higher body fat levels, another common scapegoat, processed meat, showed a clearcut and unquestionably beneficial relation to high bone mass in the Wosje study (Wosje. 2010). On the other hand, dark-green and deep-yellow vegetables (eg, spinach, romaine lettuce, broccoli, carrots, and sweet potatoes), though not something you will usually see among the favorite dishes of most kids, adolescents and college students, would probably have prevented the twens in the Washburn study from being eligible to participate in the trial, in the first place. Why? Well, the BMI and, more importantly, the body fat levels of the veggie (+meat ;-) eaters would probably have been way below the obesity cut-off for the Washburn study.
If there was a single take home message from this study, one that probably won't apply to you, a seasoned physical culturist and avid trainee, though, but maybe for your sedentary niece or nephew, it would unquestionably be that physical culture does not start at the Olympia level and that doing something is better than surrendering to your "bad genes", the greatest influence of which oftentimes is inherited laziness and the stubborn adherence to a lifestyle of which even young adults should know that it will get them right into the clutches of the pharmocracy.

References:

1. Shaibi GQ, Cruz ML, Ball GD, Weigensberg MJ, Salem GJ, Crespo NC, Goran MI. Effects of resistance training on insulin sensitivity in overweight Latino adolescent males. Med Sci Sports Exerc. 2006 Jul;38(7):1208-15. 
2. Shaw I, Shaw BS. Consequence of resistance training on body composition and coronary artery disease risk. Cardiovasc J S Afr. 2006 May-Jun;17(3):111-6. 
3. Taveras EM, Berkey CS, Rifas-Shiman SL, Ludwig DS, Rockett HR, Field AE, Colditz GA, Gillman MW. Association of consumption of fried food away from home with body mass index and diet quality in older children and adolescents. Pediatrics. 2005 Oct;116(4):e518-24. 
4. Van Etten LM, Westerterp KR, Verstappen FT, Boon BJ, Saris WH. Effect of an 18-wk weight-training program on energy expenditure and physical activity. J Appl Physiol. 1997 Jan;82(1):298-304.  
5. Washburn RA, Kirk EP, Smith BK, Honas JJ, Lecheminant JD, Bailey BW, Donnelly JE. One set resistance training: effect on body composition in overweight young adults. J Sports Med Phys Fitness. 2012 Jun;52(3):273.
6. Wosje KS, Khoury PR, Claytor RP, Copeland KA, Hornung RW, Daniels SR, Kalkwarf HJ. Dietary patterns associated with fat and bone mass in young children. Am J Clin Nutr. 2010 Aug;92(2):294-303. Epub 2010 Jun 2.

Meta Analysis Confirms: Strength Gains Depend on Training Status, Age, Workout Frequency, Rest Intervals & More

Image 1: Johanna Quas (86), "Germany's Fittest Granny"; check out this video of her on the high bar to see an extraordinary exception proving the rule - everybody who believes he/she could rival Johanna's gymnastic skills, could try that at the next world cup, where she probably will be competing again.

"Rodents are no little human beings", you will probably have heard or read this sentence at least a hundred times by now, but have you heard someone say "3 sets are not 1 set", "women are not men" or "8 weeks are not 16 weeks"? No, well in that case, a recently published meta-analysis of 45 primary strength training studies involving 1712 participants by Michael Fröhlich, Lutz Links and Andrea Pieter, is for you (Fröhlich. 2012).

Age, sex, training status, ... a hell lot of things to consider

The scientists from the University of Saarland and the Deutsche Hochschule für Prävention  und Gesundheitsmanagementin Saarbrücken conducted an extensive analysis of the respective training outcomes depending on individual preconditions of the subjects and study specific methodological variables like

training status,  gender,  age,   duration of the study,

total number of workouts, training frequency, periodization, number of sets, rest times between sets

and came up with a whole host of interesting results. And though the main utility of the effect sizes the researchers calculated based on data that was pre-coded according to an adapted scheme from Rustenbach (2003) probably is to enable other scientists to design trials that will yield significant results, the dependence of the "distinctness" of the study outcomes on one or more of the aforementioned parameters could also tell you something about how to interpret study data and maybe even about the efficiency of your own strength training routine.

The average training routine performed by an average trainee

If we take a look at the "average study" from Fröhlich et al. comprehensive dataset, we can identify the following characteristics:

• average exercises: 5 exercises
• average duration of the study: 12.5 weeks
• average number of workouts: 36.25 workouts total
• average number of workouts / week: 2.62 workouts/ week

The average subject was a 26.9 year old untrained (66% of the studies) male human being and had to perform leg extensions, leg presses or squats for the lower and bench presses, biceps curls and lat pulldowns for the upper body (exercises in order of frequency).

What if...? Personal, intervention and workout specifics influence the effect sizes

Even non-experts should not be surprised that Fröhlich et al. found significant effects (p < 0.001) for both the total study duration, as well as the total number of workouts:

Figure 1: Effect sizes according to training status, subject age, no. of workouts per week, no. of sets per exercise, and rest between sets (data adapted from Fröhlich. 2012)

As figure 1 goes to show, there were yet a number of other significant (*p < 0.05) or highly significant (**p < 0.01; ***p < 0.001) parameters which may be regarded as being predictive of the significance of the study outcomes, or - put more simply - whether or not the training intervention yielded a measurable effect.

A tale of trained and untrained subjects and different training regimen

Image 2: While sex doesn't matter for rookies, trained women are having a harder time gaining strength than men.

In addition to the data in figure one, Fröhlich et al. identified a couple of other interesting cross-dependences, such as:

• a significant difference between the effect sizes in trained men (F=1.5) vs. women (F=1.19), despite no difference for all subjects
• there was no significant difference between hypertrophy (F=1.01), strength-endurance (F=0.97) and coordinative strength training (1-4 reps a 70%-100%; F=1.23) as far as improvements in strength across all subject groups were concerned; despite their non-significance the data does thusly confirm conventional training wisdom about
• contrary to the global analysis the sub-analysis of untrained subjects revealed a statistically significant  influence of periodization on the effect sizes, with F=1.00 for non-periodized and 1.37 for periodized protocols

Of particular importance in the context of the ongoing discussion about the value of studies involving previously untrained subjects is also the following translated statement from the discussion of the results: 

[...] the strength increase in untrained subjects is very high at the beginning of the study. In the course of the training intervention, it is more or less continuous, but the performance increase per time unit is [...] continuously decreasing. This means that the adaptation curve is flattening out as the level of performance increases.

Now, this is not a new result, yet still one, why you, someone with say 3 years of regular strength training under his/her belt cannot expect the exact same +10% increase in bench press performance after 1-week of supplementation with Supplement X as Mr Trainingsnoob from study A, the producer of supplement X is referring to in his write-up.

Don't compare apples and oranges

Even in the absence of supplementation untrained subjects can achieve an average increase in strength of 25%-30% within the first 6 months, before they hit their first plateau (ACSM. 2009). You better take this, as well as the influence of other confounding variables into account, whenever you compare your own results with other people from the gym, or the anonymous subjects of scientific studies, if you do want to do yourself justice... that this also implies that you must have done something wrong, if you are / once you were a male scrawny beginner in the prime of his life and your bench or squat did not go up from say 100lbs to 130lbs within the first 6 months of your training, should be self-evident, right?

The Diet Trap Revisited: Yo-Yo Effect, Decreased Basal Metabolic Rate and the Myth of Fat-Free Mass Losses. Plus: Gender Discrimination and the "Diabetic Advantage"

Image 1: Geoffrey Cannon's "Dieting Makes You Fat" was first published in 1983 and has lost nothing of its topicality.

According to relatively recent data (Bendixen. 2002; Kruger. 2004), roughly 30–50% of the women and 10–30% of the men are currently or have recently attempted to lose weight by "dieting". I would assume that at least 90% of these dieters followed did so by just following the "Hippocratic approach" to weight loss of eating less and exercising more a strategy that is probably even more futile today, than 400BC, when it was first proposed by the father of modern allopathic medicine (cf. Precope. 1952), or 1983, when Cannon and Einzig published the first of the countless editions of their explanation for why dieting is a disaster (which is  by the way, not just because a calorie was not a calorie ;-).

Dieting makes you fat - fullstop!

From earlier as well as more recent studies on the effects of starvation, calorie restriction and exertional physical training, sleep and energy deprivation during boot camp like activities in the army, we know that prolonged caloric restriction and/or exercise induced energy deficiency will lead to hyperphagia and a subsequent "fat overshoot". As the data in figure 1 goes to show, the latter can be pretty profound and ranges from +2.7kg in the seminal fasting study by Benedict from 1907 up to 6.5kg in the well-powered (n=700) food rationing study, Fleisch et al. conducted after WW2.

Figure 1: Fat gain (in kg) after fasting, restricted eating and boot-camp like training in an energy deficit (left) and lean mass and fat loss and regain in the Minnesota experiment (data based on summary by Dullo. 1997 and  Keys. 1950)

A very similar scenario was also simulated in the so-called Minnesota experiment by Keys et al. (Keys. 1950) in the course of which thirty-two healthy volunteers were kept on semi-starvation diets for 12 weeks. During the subsequent 12 weeks their caloric intake was gradually increased until, for the last 8 weeks of the study, they had free access to food. From A brief glimpse at the data in figure 1 (right) should suffice to be able to tell that this type of "controlled re-feed" despite being conducted over a 12-week period did not prevent the +80% body fat overshoot in the subsequent ad-libitum feeding phase - and that despite the fact that the total caloric intake of the subjects had returned to baseline in week 7 of the ad-libitum phase (after temporary overshoot of up to +60% in week two, though).

Did you try to lose weight in puberty? Well that's the reason you are fat, now.

A 1999 study by Stice et al. shows that it does not even take a 12-week period of restriced eating (-50% in the Minnesota experiment) to get caught in the vicious circle of yo-yo dieting. For the 692 female teenagers from the ninth grade of a a Californian high school, even the allegedly harmless "I got to get in shape for spring" diets, were associated with a statistically significant shift in  the onset of obesity (Stice. 1999). With anxiously monitoring your caloric intake and being only marginally less detrimental than actual dieting:

• caloric restraint: +192% increased chance of early obesity (p < 0.001),
• dieting (self-labeled): +224% increased chance of early obesity (p < 0.01),
• exercise or weight control: +25% increased chance of early obesity (p < 0.01)
• (ab)use of laxatives / appetite suppressants: +85% risk of early obesity (p < 0.1)

In this regard it appears to be somewhat unfair that women are not only more susceptible to the diet trap due to the bad role models and ill advice they are presented with on a daily basis (cf. "Strong is the Better Sexy! Female Athletes as Role Models"), but - as the recent re-evaluation of existing data on the effects of dairy and/or calcium rich diets and resistance training on weight loss in 72 obese(BMI 33.4kg/m², 38.8% body fat) middle-aged (56y) caucasian men and women would suggests (Soares. 2012) - also suffer from a significantly more pronounced reduction in basal metabolic, and more importantly fatty acid oxidation rate after weight loss (-5.2kg fat; -2.3kg lean mass).

Figure 2: Basal metabolic rate (BMR) fatty acid and carbohydrate oxidation rate (FOR, COR) before and after weight loss interventions in subjects with and without metabolic syndrome (left); changes in BMR, FOR and COR in male and female study participants (data adapted / calculated based on Soares. 2012)

Irrespective of the sex of the subjects, participants who recovered from metabolic syndrome as a result of their weight loss suffered the greatest reduction in metabolic rate

• 484kj/day and 414kj/day reduction in the subjects who were either healthy or whose metabolic syndrome did not go into remission vs. 
• 670kj/day reduction in the "lucky" ones who got rid of their metabolic syndrome (criteria according to Alberti. 2009)

While Soares et al. can only speculate that these gender differences may be related to differences in either glucose or adiponectin metabolism, the initially counter-intuitive finding that the remission of the metabolic syndrome appears to predispose to future weight gain ue to reductions in basal energy expenditure bring the results of another relatively recent study to mind, in which Miyake et al. were able to show that within a cohort of  thirty obese Japanese adults with pre-diabetes (n=7), type 2 diabetes (n=13) or without diabetes (n=10) the diabetic subjects had 7.1% higher basal metabolic rates than the non-diabetic study participants (after adjustment for fat-free mass, fat mass, age, and sex; Myiake. 2011), with a statistically significant correlation between residual BMR and fasting glucose (r=0.391, p=0.032).

The diet trap and the myth of reductions in fat-free mass

Figure 3: Ratio of resting metabolic rate to fat free mass before and 4 and 8 weeks after a protein sparing fast; means, top; individual, bottom (Elliot. 1989)

Overall, these results only confirm the longstanding findings of e.g. Elliot et al. and Weinsier et al. who were able to show that the often touted linear relationship between resting or basal metabolic rate and fat-free mass does not exist - neither in the 1111 non-dieting normal subjects (118 infants and pre-schoolers, 323 adolescents, and 670 adults; Weinsier. 1997) in the Weinsier study, nor in the seven obese women in the Elliot study, who lost an average of 23kg body fat and 5kg of lean mass in the course of an 8-week modified protein sparing fast (Elliot. 1989; cf. figure 3).

So, no matter how you look at it, classic dieting may make slimmer in the short run, but whenever larger caloric deficits and faster weight loss come into play (irrespective of the amount of lean muscle you may lose), caloric restriction and exercising just to lose weight, are going to set you up for a fat rebound!