What happens if you train but don't eat enough?

Author: Ahmed Ondricka II  |  Last update: Wednesday, January 28, 2026

Your heart rate slows, there's less oxygen flow, dizziness, and fatigue.” Undereating can also cause catabolism, or when the body breaks down lean tissue like muscle for fuel, which can lead to loss of muscle mass and muscle wasting. This may be particularly noticeable for athletes experiencing undereating.

What happens if I workout but don't eat enough?

Exercising without eating well can have various consequences, both short-term and long-term. Exercising without proper nutrition can hinder your performance, slow down recovery, lead to muscle loss, weaken your immune system, and make it challenging to manage your weight effectively.

What happens if you workout and eat less?

Yes, eating less with a low-calorie diet puts you on the fast track to weight loss—and an intense exercise routine leads to increased metabolism and decreased body fat. In reality, a crash diet and overzealous exercise routine can be hard to maintain which may lead to more weight gain in the future.

What happens if you exercise but eat poorly?

Exercising without eating well can have various consequences, both short-term and long-term. Exercising without proper nutrition can hinder your performance, slow down recovery, lead to muscle loss, weaken your immune system, and make it challenging to manage your weight effectively.

Can you still build muscle if you dont eat enough?

If you don't eat enough, it will be difficult to gain muscle mass. Your body needs a sufficient amount of protein and calories to build and repair muscle tissue. Without an adequate intake of nutrients, your body won't have the necessary resources to support muscle growth.

I didn't eat anything for 16 days... This is what happened

Will I lose muscle if I barely eat?

Even if you want to lose body fat, which does require a calorie deficit, cutting calories too much can cause you to lose muscle rather than maintaining muscle while burning fat. Watch out for clear signs that your body isn't getting enough nutrients as a cue to eat more for better gains, Asche said.

Is 2400 calories enough to build muscle?

The general rule is that consuming an excess of at least 2,500 calories per week can help increase lean tissue by one pound of gained mass. This number is derived from several published studies, but it is generalized for the 'average exerciser. ' For muscle hypertrophy, your client may need even more excess calories.

What happens if you lift weights but don't eat enough protein?

Lifting and doing strength training without adequate nutrition, especially without enough protein, can actually lead to loss of muscle tissue. Furthermore, if you aren't eating right you won't have the energy to do the workouts that lead to muscle gain.

Which is an indicator of overtraining?

Symptoms and warning signs of overtraining

“It's natural and expected to feel fatigued after challenging training sessions,” Dr. Goolsby says. “But feeling like you aren't recovering between sessions or experiencing overall fatigue and difficulty pushing yourself during workouts can be indicators of overtraining.”

What happens if you exercise without eating well?

Is Working Out On an Empty Stomach Bad for You? According to Roper, fasted exercise is generally safe for most people, but it may lead to side effects. “Because blood glucose gets depleted during fasting cardio, you can experience some side effects including lightheadedness and dizziness,” she said.

What is considered a crash diet?

A very-low-calorie diet (VLCD), also known as semistarvation diet and crash diet, is a type of diet with very or extremely low daily food energy consumption. VLCDs are defined as a diet of 800 kilocalories (3,300 kJ) per day or less.

Is 1800 calories too low?

General guidelines for weight maintenance suggest a range of 1,600 to 2,400 calories for women and 2,200 to 3,000 for men. So, anything below these numbers is a low-calorie diet.

Does your body hold onto fat if you don't eat enough?

Your Metabolism Will Slow Down to Store Fat

It kicks in to preserve and store fat for future energy.

What are the symptoms of over exercising?

Here are some symptoms of too much exercise:
  • Being unable to perform at the same level.
  • Needing longer periods of rest.
  • Feeling tired.
  • Being depressed.
  • Having mood swings or irritability.
  • Having trouble sleeping.
  • Feeling sore muscles or heavy limbs.
  • Getting overuse injuries.

What happens if I exercise but don't diet?

Although exercise helps build lean muscle, a poor diet can cause muscle loss. Poor nutrition, especially a lack of sufficient protein in the diet, causes the muscles to break down for energy, preventing the growth of lean muscle and depleting the body's already existing lean muscle stores.

Will I lose muscle if I don't eat enough protein?

When on a weight loss journey, lack of protein is a huge culprit of muscle loss. “Our bodies don't store protein like other nutrients, so it's important to eat the right amount every day,” says Kate. “Everybody is different and will have different protein requirements.

What are two signs you may have over trained?

Symptoms of stage 3 overtraining syndrome (parasympathetic overtraining syndrome) can include:
  • Fatigue (feeling extremely tired all the time).
  • Depression.
  • Losing motivation to train or be active.
  • Bradycardia (an unusually slow heartbeat, lower than 60 beats per minute at rest).

How many days a week should I workout?

do at least 150 minutes of moderate intensity activity a week or 75 minutes of vigorous intensity activity a week. spread exercise evenly over 4 to 5 days a week, or every day.

Why am I gaining weight despite working out?

So, as you start working out regularly and building strength, the new muscle you build may eventually weigh more than the fat you've burnt off. (Learn more about muscle weight vs. fat weight.) It often takes at least a month or two to add enough muscle to tip the scale, so don't be surprised if it happens.

What happens when you workout hard but don't eat enough?

Even if you manage to push through a workout made difficult by a lack of fuel, your muscles can't rebuild, and your body may even resort to using the protein from your muscles themselves. Runners that chronically underfuel and overtrain are at risk of developing Relative Energy Deficiency in Sport (RED-S).

Can you gain muscle without eating a lot?

Build muscle without bulking — this was thought impossible because your body needs a lot of energy for muscle growth. However, research clearly shows that you can build muscle without bulking as long as you're in a small to moderate calorie deficit (< 500 calories).

Is 100 grams of protein enough to build muscle?

Experts differ on what the exact amount of protein you need to build muscle, but the general consensus is that if your goal is muscle gain you should consume 1 gram of protein for every pound of your target body weight. So if you want to weigh a muscle-stacked 185, that's 185 grams of protein daily.

How long does it take to recomp a body?

How long does body recomposition take? It's highly individual because everyone has a unique starting point. However, most new trainees can see noticeable improvements in their physique within 12 to 16 weeks.

Can you eat whatever and still gain muscle?

While you can certainly eat whatever you want and gain weight (assuming you are in a caloric surplus), the types of foods (macronutrients) you consume can and will impact your lean muscle growth, fat gain, and performance.

How to bulk correctly?

Bulking for beginners
  1. Eat at a caloric surplus. ...
  2. Eat moderate protein and fat, and a substantial amount of carbs. ...
  3. Lift heavy and focus on a moderate rep-range. ...
  4. Avoid "dirty bulking" to avoid excess fat gain.

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