What Happens If You Lift Weights but Don’t Eat Enough

When first getting started in the gym it’s likely that you are getting started at an early age (still living with parents) or have been living a sedentary life (desk job) and need a change. In either case the main driver is usually to build as much muscle as possible. 

It’s also likely that when starting out your dieting and nutrition knowledge is very low, you might know what calories are and the different kinds of macronutrients however if you follow the recommended daily guidelines for caloric intake then you are not primed for lifting weights. 

Lifting weights is a simple process however the building muscle aspect is actually a more hormonal and chemically complicated process. One key issue when someone first starts training is that they don’t eat enough to support muscle growth. 

What happens if you lift weights but don’t eat enough? A caloric surplus is often required to lift weights and build muscle efficiently. In the absence of readily available macronutrients to fuel and recover from a workout the body will start to break down proteins in the muscle and use body fat as a source of fuel instead. 

Even if you are currently overweight and have a high body fat percentage this is likely due to overeating in comparison to a very low level of energy expenditure. 

If you want optimal results from lifting weights then you need to be in a caloric surplus on a daily/weekly basis in order to not only fuel a workout but to recover and grow. If you do not consume enough calories in your diet then the body will break down muscle tissue and body fat to use as an energy source. 

What Happens If You Lift Weights but Don’t Eat Enough

One of the most important things to cover when lifting weights is to not only ensure that you are eating enough but to ensure you are eating enough of the right foods. 

If you consume a high majority of foods that are not nutrient dense and don’t cover your basic macronutrient requirements then not only will you struggle to see results in the gym but you will also likely experience a negative impact on your physique. 

Lifting weights is the process of contracting a muscle against a load (mechanical tension) to create enough metabolic stress in order to start the process of protein synthesis (hormonal process for building muscle). 

When in protein synthesis your body is in an anabolic state (muscle building) and requires two key components to efficiently follow through with this process and they are sufficient rest to allow the body to recover and grow and also a sufficient protein intake. 

Eating enough is a bit of a vague term, lifting weights puts a strain and demand on the body which requires a certain amount of calories to recover and grow from and these calories should be made up of an ideal split based on the individual. 

Below I will give a quick example using myself as a reference point. There are certain quantities that will work differently for each individual based upon your biochemical makeup however a base guideline is always good to use and then adjust from. 

Not eating enough will however impact your progress when lifting weights in the long run so keep this in mind if you are new to the world of lifting weights and improving body composition. 

Example Calorie Requirements When Lifting Weights

At the time of writing I’m a 6’1 male, weighing 185lbs at roughly 12% body fat (little high for my liking but I’m currently on a strength based training program so as long as my abs stay visible I can live with it). 

It’s also worth pointing out that I’m a training individual so my body can better utilize calories to support my training than someone who is just starting out. With this in mind, when lifting weights there is a certain amount of calories that you need just to maintain weight. 

All of the information I have included play a part in this as well as my level of daily activity. With all of this factored in you have your maintenance caloric requirements. This is how many calories you need just to maintain weight on a daily basis. 

To work this out individually is you can either check out an online calculator by searching maintenance calorie calculator or I can walk you through this manually in my article here:

Bulking for beginners

For ease of reference we will say that in order to maintain my current weight then I need to consume 3000kcal each day (it’s a bit more but this number is easier to demonstrate with). 

Therefore factoring in my lifestyle and current weight, my baseline needed just to maintain my physique is 3000kcal. If however I increase the intensity of my workouts and find that I’m losing weight then I would need to readjust this number and up it further to a point where my weight is stable. 

It’s important to note that these are all guidelines for you to follow and make adjustments based on how you respond to the daily calorie intake. Everyone is different and therefore the only way to understand your body is through experimentation and trial and error. 

Once you have this figure then the most important thing to cover when lifting weights is your protein requirements. Protein is the building block of your muscles and is what is needed for repair and growth. 

If you don’t consume enough calories when lifting weights then getting your protein requirements should be enough to hold or minimize muscle loss as a result. 

For most, a good rule of thumb is to consume around 1g of protein per 1lb of body weight per day. Therefore using myself as the example I would need to consume 185g of protein each day to cover my requirements. 

Carbohydrates and fats can both be used as energy sources however carbs when broken down into sugars and ultimately glycogen in the body are actually the fuel source for your muscles. Therefore it’s important to have muscle glycogen available before and during your workout as well as replenishing glycogen stores afterwards.

As you might be starting to see, lifting weights is a process that involves macronutrients not only to function when lifting weights but without a sufficient quantity of each your performance and physique will suffer.

If you don’t eat enough when lifting weights then not only will you struggle for energy to get through the workout but you will also struggle to recover fully in between each session which then leads me on to my next point. 

Will You Still Gain Muscle If You Don’t Eat Enough

People often wonder if you can still gain muscle if you don’t eat enough, there are always exceptions and outliers to any rule when it comes to human biology however for the most past if you don’t eat enough (especially when it comes to macronutrient requirements) then not only will you struggle to build new muscle but you might actually be at risk of muscle breakdown and degradation meaning that you could actually lose muscle mass.

The muscle building process is brought about by the hormonal process of protein degradation (catabolic) and protein synthesis (anabolic). When you are in a catabolic state your body breaks down protein from muscle tissue whereas an anabolic state involves building muscle tissue. 

Therefore the aim of the game when lifting weights should be to make sure you are in an anabolic muscle building state for a longer period of time than you are in a catabolic state. These states are brought about by everyday factors and it is a natural process. 

Skin cells for example die and then your body generates new skin cells in its place, the body is always in a state of breaking down and building up so you shouldn’t get too hung up on this. You enter a catabolic state when you sleep because there is no supply of food, this is natural and you shouldn’t therefore skip sleep to try and grow muscle. 

The aim of the game as mentioned should therefore be to remain in a state of protein synthesis for as long as you realistically can. Consume protein kick starts this process as does weightlifting. 

When you don’t eat enough calories however, particularly where protein is involved then it becomes very difficult to gain muscle. You simply won’t have the availability of protein in order to facilitate the muscle building process. 

The more lean muscle mass you carry the more protein you need to consume in order to just maintain it, this is because more muscle mass requires the body to use more energy just to do everyday tasks. Therefore the body will not facilitate high levels of muscle mass if you don’t provide sufficient nutrients to help it to do so. 

I’m not saying there will be drastic results if you don’t consume enough calories each day however, if you want to build muscle mass then it’s important to have a surplus of calories available to both fuel and recover from workouts.

This is with the assumption that you are lifting weights to build muscle with the intentional phrasing of ‘don’t eat enough’ meaning you are falling short of a caloric target.

if however you are intentionally consuming a calorie deficit with the intention burning body fat but will still be lifting weights then it’s worth checking out these two articles that cover it in more detail:
Progressive overload even on a cut
Keep lifting heavy when cutting

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