We all know about losing strength on a diet. I sure do. Most bodybuilders do. Any time I make a reduction in calories and limit carb intake, my strength goes into the gutter. What I’ve always found interesting is that a lot of the top-end strength — max weights and max reps with lighter weights — tends to take a pretty substantial hit within the first 2-3 weeks. For reasons I’ve yet to figure out, the squat takes the biggest and most direct hit. Benching and overhead work suffer, albeit to a lesser degree. The deadlift slumps a little; I won’t be able to approach max lifts but the 80-90% range usually stays intact at the beginning.
This is my sample of one, so your observations and strength gaps will vary, but I think almost everyone can claim a similar experience. It’s easy to write it off as being tired from the diet, and certainly muscle loss would be a factor later on down the road — especially on Bro-trition plans that almost want you to lose muscle. Muscle loss doesn’t explain rapid loss of strength on allegedly muscle-sparing diets, though.
The biggest hit comes to endurance and stamina. This makes sense; with lowered energy reserves, the high-weight, low-rep work should be best preserved. Higher volume anaerobic work, which can mean anything from sets of 8+ to high-intensity conditioning methods, always suffers the most. General work capacity, the ability to stay active and springy for the duration of a normal weight-training workout, diminishes.
Most of this can be explained by the calorie deficit. But it’s always felt, to me, like strength loss in the heavy stuff, especially that rapid loss of squat strength, had another factor behind it. I know ‘fat is strong’ and all that, with a big strong bloated midsection being great for squatting. But it doesn’t make sense that a lift would take such a hit right off the bat. The quick strength loss can’t be due to muscle loss, not that soon into the process.
Central fatigue would explain it nicely. A tired body creates a tired brain. Rather, a tired body is a tired brain. A calorie-deprived, glycogen-depleted body can’t manage the same performances it could with a full battery.
Central fatigue is the loss of performance due to changes in activity of the brain or spinal cord, changes which are triggered by an avalanche of signals from the body. You read that right — what we call ‘neural’ fatigue results from neural and chemical signals everywhere else in the body.
The brain oversees the universal stress response through the hypothalamus, which regulates both adrenal and reproductive hormones and the immune system, among other symptoms. Getting worked up mentally or emotionally filters down to physical symptoms.
Fatigue is task-dependent. You get tired in different ways depending on the activity. There will be cases where muscular fatigue is the limiting factor. Other instances limit performance at the brain and spinal cord.
Get the body tired and the brain follows. It helps to stop thinking of the brain and nervous system as independent units, separate from the rest of the body. Living organisms don’t work that way. Stress is universal. Exercise affects muscle and central-neurological factors, which include the endocrine and immune systems. You don’t just train your muscles; you’re training the whole body.
This is why I’m skeptical about the usefulness of acute hormone changes, the testosterone and cortisol and growth hormone spikes that everyone worries about. These hormonal spikes and depressions are superficial, the symptoms of a deeper issue. Affect the real cause and the hormones will fall in line.
When you get tired during exercise, it’s not just your muscles wearing out. The entire motor-control system gets worn out up in the CNS. You lose the ability to generate maximal contractions, and to sustain sub-maximal contractions, which can lead to wackiness. Wackiness like increased injury risk. Awhile back I came across these two studies:
These papers show a reduction in central motor control when fatigued — the effect happened even in the unexercised limbs — which may lead to an increased risk of injury. That’s not a surprise in itself. We can always blame poor form and execution for injuries; being tired during a complex and relatively high-risk movement is begging for trouble. High-skill movements don’t mix with fatigue.
What I find interesting here is the central-level effect. The injury risk isn’t increasing because of tired muscles. Motor control isn’t suffering because these girls ‘broke down muscle fibers’. We’re observing these effects because tired muscles create a tired brain. The CNS is worn out, which causes motor control to suffer.
Calorie restriction signals specific effects in the brain. Reduced levels of amino acids, especially tryptophan, affect the hypothalamus and hippocampus, filtering into the endocannabinoid and dopamine networks that affect your behavior, mood, and motor control.
The serotonin hypothesis of fatigue has been around for years. Serotonin is associated with lethargy, anxiety, depression, and generally being an unmotivated stress-avoiding slob. Changes in serotonin behavior, particularly its relationship with the hedonistic dopamine, are strongly linked to central fatigue. Poor performance in athletes is directly associated with change in serotonin behavior.
A recent-ish paper has shown that eating carb-rich ‘comfort foods’ can attenuate some of the symptoms of Addison’s disease, a form of adrenal dysfunction. It’s interesting that a deficit in the brain’s energy supply can be linked with HPA dysfunction, and that we see similar symptoms in dieters. While I don’t want to overstep my causation privileges here, I don’t think this is a coincidence; the Addison’s patient has a pathology, while the chronic dieter voluntarily limits food intake. In both cases a brain-level deficit cascades down to an organ-level problem. We see the hormone changes and intuitively blame them, when they’re only symptomatic. The real issue is in the brain.
Studies on BCAA and carb supplementation do show improvements in cognitive function and perceived effort (exercise feels less hard), but at the same time there’s not a lot of evidence behind the idea that they improve performance. I can’t help but think of the difference between normalizing a deficiency and triggering improvements above baseline — the same way that insulin-sensitizing supplements work in diabetics while having no measurable benefits to healthy folks. Restoring normal function doesn’t imply a performance gain in the already-normal.
Carb-depleted muscles send out their own signals. When you train a muscle under normal fed conditions, you get the usual indicators of damage and inflammation, but there’s plenty of energy to trigger the anabolic recovery process. Take away the precious glycogen reserves, and that changes. Muscles depleted of glycogen release more inflammatory cytokines, metabolic waste products (like ammonia), and the overall anabolic response is diminished while competing energy-conserving systems switch on.
Exercise and weight loss do tend to favorably improve inflammation in the obese, as obesity can be thought of as a disease of chronic inflammation. But again: what’s good in an unhealthy population doesn’t always work the same way in the healthy trying to push to extremes in a sport. Moderate exercise and maintaining a healthy body weight are positive effects. Chronic, excessive exercise — the way most ‘exercise fanatics’ like to train, when left to themselves — elevates inflammation. Reasonable, limited amounts of exercise are good. Repeated muscle-smashing sessions, in strength or endurance, probably aren’t.
Low-carb, low-calorie diets are probably enhancing central fatigue even if eating more won’t improve performance in well-fed people. Central fatigue is a protective effect, remember. Neural output scales back to avoid injury. You feel like crap so you’ll stop the behavior and rest. In physiological terms, calorie restriction triggers a kind of stress — some of which is beneficial, mind you, but only if you don’t go out of your way to make problems with stupid workout routines.
As long as you’re not pulling a Traditional Contest Diet, which is to say starving yourself with chicken and broccoli while spending two hours a day on the treadmill, I think you’ll adapt to the lowered calories within a few weeks. Martin’s Leangains method gives the option to train fasted, which sounds counter-intuitive, but I’ve found it to be fairly effective if the training is right and if you allow some time to get used to it. Those of you accustomed to a 50-set body-part workout and pre-workout shake with 300g of carbs may be in for a shock. But you’ll adapt. I find that I enjoy fasted training as much or more than training fed, provided I have enough stimulants in me.
Despite the original dip in strength, you can still make gains on a diet ranging from mild progress to pretty damn good improvement. Your real rate of progress will be a function of the calorie deficit, your conditioning coming into the diet (conditioning as work capacity and as ‘peakedness’ of strength), your lifetime experience (a guy benching 500 lbs for reps can expect a different maintenance-improvement curve from a guy benching 250), and how well you adapt to low calories.
Because of the central fatigue effects, I think there’s a strong case to be made for using supportive gear during a diet. Use a belt on big lifts. Use straps on pulls, if you need them. Dieting doesn’t mix with big lifts, but you can at least mitigate some of the damage. Using equipment can help take some of the mental focus off those trouble areas (like abdominal pressure and contraction, or grip) and, in the case of the squat, you’re probably getting a boost from the intra-abdominal pressure.
That’s a total guess mind you, but I’m going by what I feel when squatting well-fed, and squatting after 4-6 weeks of a diet. My gut just feels emptier and more fragile, and the ratio between belted to unbelted squat reinforces the idea.
The balance between frequency and volume has to change. Strenuous exercise creates a big dent in recovery ability and increases inflammation, which isn’t a big deal if it doesn’t happen often. Chaining yourself to the treadmill and continuing your Bro-volume workout sessions isn’t the best of ideas while trying to diet without drugs. Previous conditioning and work capacity will come into the picture, of course, but it’s probably a good idea to slash your usual volume in half (at least) if you’re used to annihilation-style workouts. It doesn’t take that much work to maintain muscle.
I think frequency can be kept fairly high as long as you’re willing to scale back the number of strenuous workouts. Low-intensity cardio in small amounts can be done daily. You can even lift daily if you keep the effort in check and don’t go nuts with the tonnage. The idea is not doing less; the idea is to do less of the stuff that you can’t recover from.