As far as the body’s concerned, the ideal scenario would occur when energy intake perfectly matches energy expenditure. We also know that it will fight to stay there, and there are very important reasons for our body to try to maintain this homeostasis or ‘unchanging” state.
Because energy imbalances can affect a lot more than weight gain or loss. Drastic changes in energy balance can impact other processes in the body, such as reproduction, cognitive functions, metabolic functions, repair, and regeneration.
In athletes or highly active individuals, energy deficits can impair the resynthesis of muscle and liver Glycogen, as well as the stimulation of protein synthesis. This means that our bodies don’t properly repair and restore from exercise since with a negative energy balance, the body is always functioning in a catabolic/breakdown state. With energy reserves being used to maintain a minimum level of function, there’s little left over for rebuilding and repair.
In general, the macronutrients (proteins, carbohydrates, and fats), micronutrients (vitamins and minerals), and phytochemicals we eat are broken down into smaller sub-units such as amino acids, glucose, fatty acids, etc. These nutrients are taken up by our cells in particular ways, they provide potential energy, and they can act as co-factors for chemical reactions in the body. They stimulate the release of hormones, and they provide raw materials that can be incorporated into our body structures, including tissues and organs.
Even though not everyone responds the same way to the digestion and absorption of specific foods, or the uptake of specific nutrients into the cell, 99.9% of people do. Recent nutritional research suggests that the basic mechanism is the same but there are intriguing individual differences likely due to our unique genetic makeup. This code provides cellular instructions for making proteins. But genetic polymorphism and nutrigenomics, though interesting, are out of the scope of this article. So, while we shouldn’t eliminate food groups because they all work together synergistically, I am going to focus on the proteins we consume from food, that are synthesized into the ‘building blocks’ for the production of ‘new’ proteins needed for the growth and repair of tissues.
The RDA guideline for protein is 0.8 grams per kilogram of body weight per day. But athletes and lifters concerned with their performance or physique require more protein than that. And when healing from injuries, broken anything, or tissue trauma, we may need as much daily protein as recovery from heavy strength training or even more.
The researchers concluded that “…the range of 2.3 to 3.1 grams per kilogram of FFM (fat-free mass) is the most consistently protective intake against losses of lean tissue.” In other words, for every kilogram on your body that’s not fat, you should be consuming 2-3 grams of protein in order to preserve lean tissue.
In short, when injuries occur, we have to pay special attention to supplying our body with enough of these building blocks for repair. And why we often feel or hear that DOMS are worst, pain comes back, and injuries relapse while on a caloric deficit.
Whether it is tissue repair or muscle damage, our body is under stress and what happens can be summed up in three stages:
Inflammation, which draws healing chemicals to the injured area. Proliferation, which removes damaged tissues and rebuilds temporary new tissue. And remodeling, where strong more permanent tissue replaces the temporary tissue.
Until all these stages have taken place, a caloric deficit is not recommended. Remember that the goal of training is progress and adaptation, not being tired or sore, much less unrecovered completely from an injury, if there is pain, something may not be completely healed and need a bit of special care, including, rest, sleep, and proper nutrition.
To sum it up: Repair of any kind is a longer process than we might be willing to allow, but if we attempt a caloric deficit, nutrients tend to go to basics/survival needs instead of repairing. Injuries and pain are usually felt more and heal slower. It is mainly the basic science of catabolism/anabolism. Injuries need a bit of extra protein, so make sure you add a bit more than usual to help with the healing process and wait until it is all healed up and then some before resuming activities. Remember that muscle memory is a thing and no matter how much muscle/strength you may end up losing, you’ll be able to gain it back much faster than you initially gained it.
Clarifications from reader’s questions:
Protein requirement is not a number set in stone, it depends on several variables including the quality of protein ingested, age, fitness level, and of course, individual repair needs. The recommended minimum for sedentary individuals is 0.8g/Kg, this translates to about 55g of protein per day for a 150lb individual. However, this amount is not optimal but simply to prevent protein deficiency. During high-intensity training, these needs may be increased to about 1.4 to 2.0g per Kg of body mass (between 95 and 135g of protein per day for a 150lb individual). Similar increases are recommended during periods of low energy intake or low carbohydrate intake.
While these recommendations may be adequate to cover protein turnover requirements, research has suggested that higher amounts of protein in the diet may be vital for immune function, metabolism, satiety, weight management, and performance. Therefore, many experts recommend a higher intake that approaches or exceeds 1g of protein per pound of body weight.
The body has the ability to make 12 amino acids, known as non-essential amino acids. However, 8 amino acids can only be supplied by the diet and are thus termed essential amino acids. Hence the importance of daily amino acid intake through the food we consume. Small daily losses from amino acid breakdown will eventually put us in a net negative protein balance. While carbohydrates and especially fat content of the body are fairly well maintained, it’s actually quite difficult to maintain a consistent amino acid pool without dietary intervention. Managing the plasma amino acid pool is like keeping a sink full without a drain plug. If amino acid intake falls below daily amino acid degradation, things like enzymes and structural proteins are cannibalized. If this process persists for long enough, vital functions shut down. As for protein quality, animal proteins such as meat, poultry, eggs, fish, milk, and cheese, rank the highest while plant proteins rank lower. (Extracted from The Essentials of Sport and Exercise Nutrition-PN).
Further reading and other nutritional recommendations:
The Role of Nutrition in Physical Therapy:
http://www.newgradphysicaltherapy.com/the-role-of-nutrition-in-physical-therapy/
Nutrition for Injury Recovery:
http://www.precisionnutrition.com/nutrition-for-injury-part-4
Nutrition for recovery from muscle injury:
http://www.mysportscience.com/single-post/2015/10/12/Nutrition-for-recovery-from-muscle-injury
An Evidence-Based Approach for Choosing Post-exercise Recovery Techniques to Reduce Markers of Muscle Damage, Soreness, Fatigue, and Inflammation: A Systematic Review With Meta-Analysis
https://www.frontiersin.org/articles/10.3389/fphys.2018.00403/full
Vitamin C–enriched gelatin supplementation before intermittent activity augments collagen synthesis:
http://ajcn.nutrition.org/content/105/1/136.abstract?etoc
Nutritional Support for Exercise-Induced Injuries:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4672013/
Why Dieting Sucks:
http://sciencedrivennutrition.com/why-dieting-sucks/
Too little sleep and an unhealthy diet could increase the risk of sustaining a new injury in adolescent elite athletes: