If you're losing muscle while trying to lose fat, you're not alone. A lot of people struggle with losing weight. Many start by making drastic changes to their diet and workout routine which have a strong effect on the body. When someone decides they want to improve their body, the usual goal is to increase muscle and decrease fat. It isn't always that easy though.

"It is bad to lose muscle instead of fat because muscles are the key players in body movement and function. With loss of muscle mass, strength and endurance are affected negatively, leading to decreased functional performance," said Gerardo Miranda-Comas, MD, Assistant Professor of Rehabilitation Medicine, Icahn School of Medicine at Mount Sinai.

Miranda-Comas said that if you're trying to lose weight the correct way, your body shouldn't try to eliminate muscle first. "In general, muscle is not lost before fat – it is very dependent on nutrition and activity volume. A person who is attempting to lose weight by not eating may lose weight in muscle first before fat," said Miranda-Comas.

This is because your body first pulls carbs (glucose) for energy. If you're not eating food, then this isn't available. Your body then has to pull the glucose stored in your liver and muscles. "Fat is also used for energy depending on duration of the physical activity, and an individual can train their body to use fat as the primary source of energy," says Dr. Miranda-Comas. This is the premise of the keto diet.

"A healthy diet is usually 45-65 percent carbs, anywhere from 15-35 percent protein, and 20-35 percent fat. The point is having a balanced diet and not restricting any food very low," said Wesley Delbridge, RDN, spokesperson for the Academy of Nutrition and Dietetics. This varies depending on what particular diet you follow.

Here are four signs, provided by Men'sHealth, that you're losing muscle, not fat.

1.    Your workout feels more strained.

If you're losing muscle, your usual workouts may feel a lot harder than they once did. You may also feel like completely crossing off "gym session" from your schedule. "You’ll notice less strength in the gym. The weight you used to be able to do for reps may decrease or you may not be able to get as many reps as you once did for each set," said Spencer Nadolsky, D.O., author of The Fat Loss Prescription.

2.    You feel sluggish doing everyday activities.

Losing muscle will affect you in the gym, as well as throughout your normal day-to-day activities. "Inadequate nutrition can lead to a decrease in muscle, which may lead to impaired function. This is usually caused by an energy deficiency and possible overtraining. In the very active individual who is losing weight along with a decrease in performance, we must consider overtraining," said Dr. Miranda-Comas.

3.    Your body fat percentage isn't decreasing.

One of the most obvious signs to look out for is whether or not your body fat percentage is decreasing when you're losing weight. "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.

4.    You're losing weight way too quickly.

While these results may excite you, it's probably not for the best. Unless you had a lot of fat to lose at the beginning, the fast weight loss may only be attributed to a loss of muscle mass. When people experience rapid weight loss, they often aren't able to sustain it.

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