Why are my arms getting smaller even though I'm working out?

Author: Aniya Nolan  |  Last update: Sunday, July 13, 2025

With muscle atrophy, your muscles look smaller than normal. Muscle atrophy can occur due to malnutrition, age, genetics, a lack of physical activity or certain medical conditions. Disuse (physiologic) atrophy occurs when you don't use your muscles enough. Neurogenic atrophy occurs due to nerve problems or diseases.

Can your arms get smaller from working out?

  • No.
  • You can't slim any part of the body by training that body part.
  • Training the arms may cause the muscles to get bigger and the arms thus thicker, but only losing fat will cause them to appear slimmer.

Why do my arms keep getting skinnier?

Some people naturally have slimmer limbs. Body Composition: A lower percentage of body fat or muscle mass can make your arms look skinny. If you have a higher body fat percentage in other areas, your arms might stand out as thinner. Diet: Insufficient caloric intake or lack of protein can lead to muscle loss.

Why am I losing muscle mass even though I workout?

If you're not training hard enough, progressing, or you're overtraining, you can see muscle mass go down, even if you're in the gym everyday. If your calories or protein are too low, you will see a decrease in muscle mass, even if you are getting stronger.

Why are my arms not growing when I workout?

If your arms aren't growing despite working out, several factors could be at play: Insufficient Volume or Intensity: Ensure you're doing enough sets and reps with a challenging weight. Aim for 3-4 sets of 8-12 reps for hypertrophy.

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How long does it take for your arms to get bigger when working out?

Typically, it takes around 6-8 weeks for you to start noticing changes in the appearance of your arms. At around the 12 week mark, this is typically when you can expect to see more significant changes, especially if you didn't already have a large amount of muscle mass in the area!

Which muscle grows the fastest?

Muscle Groups That Grow Fast
  • Leg Muscles (Quadriceps and Hamstrings):
  • Back Muscles (Latissimus Dorsi and Trapezius):
  • Chest Muscles (Pectoralis Major):
  • Shoulder Muscles (Deltoids):
  • Arm Muscles (Biceps and Triceps):

How to tell if losing muscle or fat?

If you're losing weight but your body fat percentage is staying the same, it's probably a sign you're losing muscle. "Your body won't shape the way you want. You'll notice shrinking circumferences, but the pinch-able fat is the same," says Dr. Nadolsky.

Why am I working out but not losing weight or gaining muscle?

You may not be maintaining a calorie deficit or you could be doing too much of one type of exercise. Reach out to a healthcare provider if you are feeling stuck and need help developing a more effective weight loss plan. They can help determine the reason for your plateau and help you get back on track.

How to regain lost muscle mass?

The best exercises to build muscle include:
  1. Bodyweight exercises, like pushups, squats, planks and lunges.
  2. Strength training using weight machines.
  3. Resistance band exercises.
  4. Weightlifting with dumbbells.

What disease causes skinny arms?

Acquired generalized lipodystrophy (AGL): Acquired generalized lipodystrophy (also called Lawrence syndrome) usually results in fat loss in your face, neck, arms and legs. Fat loss associated with AGL may occur rapidly over a few weeks or slowly over several months or even years.

Does fat get jiggly before you lose it?

The Science of Fat Loss

Think of it like a balloon losing air—it deflates, but doesn't disappear immediately. Over time, your body adjusts, but the jiggly feeling can be a temporary step along the way.

Why are my arms getting thinner?

Scientists have found that a major reason people lose muscle is because they stop doing everyday activities that use muscle power, not just because they grow older. Muscular atrophy is the decrease in size and wasting of muscle tissue. Muscles that lose their nerve supply can atrophy and simply waste away.

How do you know if you're overtraining?

When you're trying to tell if you're dealing with overtraining, consider these common symptoms:
  • Your Performance Declines. The hallmark sign of overtraining, Dr. ...
  • Fatigue and Soreness Ramp Up. ...
  • You Get Sick or Injured More Easily. ...
  • Sleeping Gets Harder. ...
  • Your Mood Changes. ...
  • Other Physical Symptoms Pop Up.

What exercise burns the most arm fat?

Flabby arms? Top 5 exercises to burn arm fat
  • 1/6. ​​Exercises that'll help in losing arm fat​ Overall weight loss can lead to the lowering of fat in certain parts of the body. ...
  • 2/6. ​​Cardiovascular exercise​ ...
  • 3/6. ​​Push ups​ ...
  • 4/6. ​​Bicep curls​ ...
  • 5/6. ​​Tricep dips​ ...
  • 6/6. ​​Arm circles​

How long does it take to see results from working out 5 days a week?

As a rough guide, you'll probably notice some initial changes in the first four to six weeks, but longer-term changes (what you're working toward) will often take around eight to 12 weeks. The good news is that you're likely to start feeling better quickly.

How to flush out water weight?

  1. Exercise Regularly. Daily exercise provides several health benefits, including preventing water retention. ...
  2. Drink More Water. Drinking water to reduce water weight sounds counterintuitive, but it helps. ...
  3. Manage Salt Intake. ...
  4. Cut Carbs. ...
  5. Focus on Certain Foods and Herbs. ...
  6. Try Supplements. ...
  7. Up Your Caffeine Intake.

Why am I gaining weight when I'm eating less and working out?

Key takeaways: Working out can cause short-term weight gain as your muscle mass increases. Post-workout inflammation may cause temporary weight fluctuations. Workout plateaus, supplement use, and dietary changes can also stall your weight-loss efforts.

Is too much cardio bad for muscle gain?

In fact, newer studies have shown quite the opposite could be true: cardio doesn't inhibit muscle gain and may even help it. “In recent years, the body of research evidence indicates that doing concurrent training does not interfere with hypertrophy following resistance training,” Rosenkranz says.

What happens if you eat too few calories and work out?

“When people are eating too few calories or exercising a lot while trying to lose weight, the body reverts into a state of metabolic adaptation.” Metabolic adaptation is a survival defense mechanism that our bodies revert to when deprived of food.

What makes arms look bigger?

The triceps muscles are at the back of the upper arm. Big triceps make your arms look better, even with adequate biceps muscle. Don't neglect them. Build up your triceps with exercises like pushdowns, overhead extensions, and dips.

Which is the hardest muscle to grow?

The lats tend to be one of the hardest muscles to develop.

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