Most of the time, exercise can help with weight loss, but that's not always the case. Sometimes there are other factors at play that can cause you to gain weight even when you are trying to lose it.

Here are some reasons you could be gaining weight even if you're exercising and trying to lose weight.

You're eating too much.

Following a nutritious diet can be just as important as exercising. According to Mayo Clinic, "You gain weight when you eat more calories than you burn - or burn fewer calories than you eat."

Although you should not burn the exact number of calories you consume, if you're consuming way more calories than what you are burning during your workouts, you may end up gaining weight instead of losing it.

... Or you are not eating enough.

It may seem contradictory to some, but under-eating can lead to weight gain.

According to Jillian Michaels' website, not consuming enough calories can cause the body to begin to break down muscle and hold onto fat as the body goes into a period of starvation due to insufficient energy.

Figuring out your daily caloric needs and opting for nutrient-dense foods can be useful when it comes to avoiding weight gain.

You are not mixing up your workout routine.

Over time, the body adapts to exercise and becomes more efficient. According to Women's Health, progression and variety are key for individuals with weight loss goals.

If you just repeat the same routine, your body gets used to it and you may not build muscle and lose weight as efficiently as you would like.

In mixing up your routine, the following variables can be manipulated or varied: exercise type, intensity, duration, volume, and rest.

You are not lifting weights.

Although cardio workouts can be quite effective, weight-lifting can provide you with more calorie-burning benefits than cardio.

According to Body Building, lifting weights can help to increase your body's short-term and long-term calorie burning abilities. It can also build up your muscle mass, which can be helpful when it comes to losing fat.

Of course, there are other ways to build muscle without lifting weights.

You are putting on muscle mass.

A pound of muscle and a pound of fat both weigh the same, but muscle is more dense than fat.

According to Greatist, a pound of fat takes up about four times more space than a pound of muscle tissue, which means that although you may be losing body fat, your weight may stay the same or even increase due to your muscle mass increasing.

You need more rest.

Diet, exercise, and recovery play a huge role in weight loss. Not prioritizing rest and recovery can halt weight loss and even cause you to gain weight.

According to Daily Burn, sleep deprivation throws off our hunger-regulating hormones, which can lead to an increase in cravings. Sleep deprivation also increases the release of the stress hormone cortisol which both increases appetite and causes the mitochondria in the cells that digest fuel to shut down.

You are not accounting for normal weight fluctuation throughout the day.

You may not be gaining weight per se, you may just be experiencing normal weight fluctuations that occur for many reasons, including after you eat, drink, or exercise.

According to Livestrong, it is normal for your weight to fluctuate between two to ten pounds throughout the day.

The site suggests weighing yourself at the same time each day while wearing the same outfit and using the same scale to more accurately monitor your weight. 

You are not drinking enough water

According to Dr. Lori Shemek, mild dehydration can lead to weight gain because it can cause chronic feelings of hunger. These feelings of hunger can lead to snacking in excess or eating needlessly large portion sizes.

"The next time hunger or a craving appears, drink an 8 oz. glass of water," Dr. Shemek advised on her website. "Wait a couple of minutes and you'll be amazed at how quickly the craving or hunger disappears."

It is water weight.

In addition to our total body weight being composed of 50-60% water, diets high in sugar and sodium can cause us to retain water.

But, gaining water weight during your weight loss journey isn't necessarily a bad thing.

"This doesn't mean that you're retaining water in an unhealthy way- your body is just adjusting to your healthier eating habits," Ashvini Mashru, R.D., author of "Small Steps to Slim" told Women's Health.

It could be related to your period.

It's normal to experience a bit of additional bloating and weight gain during your menstrual cycle.

Fortunately, this weight gain is typically temporary because it has to do with water retention, according to Healthy Women.