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Can you gain muscle while dieting

Calorie Deficit & Lean Body Mass

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Posted by Paul

QUESTION

Is it possible to gain lean body mass (via resistance training), while in a caloric defict (or negative energy balance)?

ANSWER

Initially, I would be apprehensive in providing a definite "yes" or "no". There exist a number of possible contributing factors: individual differences, the nature and size of the caloric deficit, the nature of the resistance training program, unaccounted behavioral modifications (specifically diet & habitual daily activity), and the length of the 'program' to mention a few.

Let's begin. Firstly, Garrow et al (1987) observed that the 'excess' weight in obese people is approximately 75% fat and 25% fat free mass. This fat free mass we could call compensatory lean body mass (LBM), as it is laid down in the body to assist with supporting the excess weight and assisting in moving a body with increased inertia.

In a calorie deficit state, after the first few days where initial weight loss is predominantly due to fluid and stored glycogen/carbohydrate loss, weight loss is due to the loss of fat and LBM. Webster et al (1984) illustrated that with a moderate calorie deficit in the obese 25% of the total weight lost is LBM and the other 75% is fat. Does this represent the loss of the compensatory LBM, or 'regular' lean body mass? Similarly, recent readings (?) seem to suggest that the greater the calorie deficit, the greater the LBM loss.

(I tend to suggest that the loss of LBM would predominantly be muscle tissue in addition to the compensatory {connective?} tissue. I base this on two thoughts. Firstly, that the fast twitch or type II muscle fibres are catabolised given that hey are more metabolically active; and, secondly, as an evolutionary adaptive response, habitual daily activity would be reduced, particularly that of an intense nature. The reduction in daily activity would itself stimulate an atrophy/catabolism of muscle tissue. These points become relevant again when discussing the nature of the resistance training program. See later.)

This is an imperative point. In 1985 Danforth indicated that four general factors contribute to daily energy expenditure, assuming no heavy labour/exercise demands:
(1) resting metabolic rate (RMR), 65-75%,
(2)thermic effect of exercise, 15-20%,
(3) thermic effect of food, 10%, and
(4) adaptive thermogenesis, 2-5%.
RMR is largely determined by LBM, up to 70-75% (dependent upon initial body composition and general status of the neuro-endocrine systems). This equates to approximately 50% of total energy expenditure due to LBM. If LBM is lost as a function of weight loss, a large avenue for daily energy expenditure is reduced. After this loss a relatively smaller calorie intake is required to maintain the new body weight/composition. This is a noted factor in the yo-yo cycling of weight loss and fat gain with relatively persistent on-off dieters.

What does this mean for the general scenario? Provided no additional exercise is started and a calorie deficit is initiated by a reduction in calorie intake we are going to loose some LBM, the amount dependent upon the size of the calorie deficit. Again one of the reasons why a 'slow' approach to weight loss (approx 1% of body weight per week) is recommended.

Now if we add exercise to the scenario! If calorie deficit is achieved by an increase in energy expenditure (over normal daily average), and not through any change in diet (content, amount & behavior) what happens? Good question! It would depend upon the nature, duration and intensity of the activity, and the length of time this (increased energy expenditure) calorie deficit is induced for. Here I would need to assume that no compensatory or reflexive decreases in daily activity happens (as is often the case when significant changes in lifestyle are made, again an evolutionary/homeostatic control mechanism linked to behavior {from observation}). Sure, some activity is recommended often in addition to a relatively small reduction in calorie intake. This helps ensure that enough calories are consumed to ensure adequate intake of macro- and micro-nutrients and that less lean body mass is lost (thereby reducing the size of reduction in LBM).

Which activity or exercise mode is most appropriate? The answer to this is dependent upon the individual: their likes, dislikes, preferences, accessibility, etc, and not to any particular piece of research. OTOH some forms may be more effective, safer and more desirable than others. Aerobic endurance activities can be of benefit for various reasons, particularly in relation to the energy/calories expended over time during the activity and the post-exercise oxygen consumption in comparison to 'anaerobic based' activities. OTOH, I often wander if low intensity long duration (LILD) - which is not always the most appropriate form of aerobic activity for all people all the time - activity may contribute to the loss of LBM. It appears that (ST?) muscle fibres decrease in diameter to improve the oxygen transport dynamics. If this is the case in LILD, and is couples with a catabolism of FT fibres, the loss of LBM may not be as prevented as much as it could be. The nature of the LILD activity (weight-bearing or not, size of muscle mass involved, muscle mass used relative to habitual activity) would be confounding factors in determining this effectiveness.

The question specifically pertained to resistance training. Now resistance training is a general term that can incorporates various external sources (such as exercises using body weight, projectiles, free weights, machine/apparatus, tubing, and partners) and internal forms of resistance (isometric contractions; after Bompa 1983). Resistance training in the form of weight training - using free weights (barbells & dumbells) and various types of 'machine' resistance - is the most common form used, especially in health clubs and gymnasiums. The scenario can be, and often is, for athletes. Weight training can be used to bring about various structural & functional adaptations. The exact nature of these depends upon the initial training status, experience and expectations of the participant in addition to various factors of the weight-training program: Exercise choice, total work done (load or intensity, no. of sets, no. of reps, time of sets or speed of execution, length of rest between sets. frequency of the exercises performed per week, and the length of the program. These factors are important to consider.

Here is where I see a large limitation in much of the research that has been done in this area (resistance training and weight/fat loss), and probably suggests why only indirect means (and those through anecdote & observation) can provide insight into the question. Much research has been done on beginners, those new to weight training. This, in addition to the large variations in research design (particularly program prescription, and dietary change), creates a number of issues. Many of the early changes or adaptations in the first 6 to 8 weeks (nearly the length of some research projects!) are predominantly neural. They mainly involve alterations in the intermuscular and intramuscuar recruitment patterns (participants become more coordinated, and energy efficient, with the exercises they perform) simultaneously with a disinhibition mechanism. Is this initial neural adaptation enough to reduce the loss of, or increase, LBM ? Another good question! I suggest research on beginners is again limited here because of the necessary ethical, and common sense, application to be progressive with the overload. The initial loads - and some of the 2x20reps at probably 50 RM loads I see prescribed in health clubs/gyms for isolation exercises kills me - may not be intense enough to stimulate a large portion of the muscles (include. the FT motor units) involved to stimulate further protein synthesis, beyond the initial muscle soreness stage. Given that many of the adaptations related to weight training - in this case increased muscle mass (LBM) - will occur from multiple exercises and sets of 12-15RM loads (or heavier) for a considerable period of time (6 to 8+ weeks), much of the research may thus be inappropriate. Similarly, the research conducted on females - pardon the generalisation - also confronts the often held fear of "building big muscles" and "becoming butch" that is likely to have a negative effect upon 'attitude' to more intense loads.

In sum, it may well be possible to add LBM (muscle mass) while in a caloric deficit given that the participants are relatively untrained and the program is 'appropriate'. By appropriate I mean long enough (6-8+ weeks, ongoing?) intense enough and focuses on all major muscle groups and preferably uses a relatively frequently changed array of compound exercises. I make this qualification on the basis that if not all muscles and all motor units (hence the variety) are 'optimally stimulated the protein loss (catabolism) may still occur in the unworked muscles as the body struggles to readjust its evolutionary & genetically defined homeostatic mechanism in response to reduced calorie intake. On this basis, if the resistance/weight training program is new to the individual and produces a caloric deficit in itself, be wary of inducing a greater deficit through energy intake restriction (our bodies and minds tend not to cope well with large changes for extended periods of time, hence the failure of "quick fix" diet & exercise regimes). A slightly increased intake of protein may be warranted too!

The scenario would be different for someone who already is well (adapted to and) adept with weight training and possess a relatively low percentage of body fat. Although a somewhat extreme scenario, bodybuilders highlight this. In the weeks leading up to their competition/s they need to find and maintain a fine line between the balance of (mood & behavior swings with ) catabolism (induced by sometimes extreme calorie deficits, although their diets are often very high in protein) and anabolism. Really, they do not win this battle. They do loose muscle mass (with their amazing body fat losses), what they aim to do is minimize the loss.

All this tends to suggest that adding LBM through resistance/weight training is APPARENTLY possible. From a fundamental basis I still question the likelihood. Muscle tissue is far more metabolically active than fat, so to add muscle mass while losing body fat on a calorie deficit may be IMPROBABLE in the long term. Sure, the energy derived from the breakdown of fat may assist in the synthesis of protein (LBM) obtained from the diet under the stimulus of resistance/weight training. OTOH, the synthesis of the LBM and its maintenance ultimately requires a calorie surplus. Extra "work" is being done. This cannot be done in a calorie deficit state (indefinitely). Something cannot come from nothing, I think!

Last Note: Weight & fat loss issues, I believe, have far more to do with socio-cultural and psycho-emotional factors than the simple energy balance mathematical issues dealt with here.

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