Working Out But Gaining Weight, Why?


Written by 1FW Training Program Director, Keith Baumgard

Believe it or not, gaining weight at the beginning of a new exercise program is quite standard. Not only is it common, but it is normal. If you have not exercised regularly in months, you can expect to add a couple of pounds at the beginning but have no fear, this weight gain is good weight gain, and it will do nothing to keep you from reaching your goals as long as you understand what is going on.

First, you have to understand increased energy reserve capacity.

Let’s assume that your calorie intake isn’t 500-1000 calories above maintenance levels on a daily basis. This is a safe assumption to make as most weight losers don’t come anywhere close to eating maintenance calories. In fact, they tend to under eat (finding out if you’re not eating enough calories to lose weight). So then, if your calories are below maintenance levels, how could you possibly be gaining weight – especially if you’ve been exercising too?

Your body stores energy in two main ways – fat and glycogen:

Fat storage is fairly linear – meaning it fluctuates slowly based on your current lifestyle. However, glycogen storage can swing wildly on a day to day basis depending on the type of exercise you do, the amount you do, and how long it’s been since you’ve done any exercise.

Glycogen storage – Your body mostly stores glycogen in the muscles, but it also stores it in the liver. Glycogen comes from glucose, which comes from eating carbohydrates (or protein via gluconeogenesis). When we eat carbs, our body breaks them down into glucose. That glucose enters the bloodstream, and any extra is taken up by insulin and stored as glycogen in the muscles and liver.

Here’s the thing, though; that glucose is combined with water to form glycogen. In fact, every gram of glucose is stored with about 3 grams of water. Taking that one step further, the average person can store about 15 g/kg of body weight of glycogen [2]. So let’s do a little math:

A 200-pound person weighs about 90kg

At 15 g/kg, that person carries 1350 grams of glycogen (15 * 90 = 1350)

1350 grams equals 3 pounds (1350 / 453 grams in a pound = 3 pounds)

That’s right, 3 pounds of glycogen is what this person stores on average in their muscles and liver. If he were going from a sedentary lifestyle to a very active one, the swing in intracellular water weight could be several pounds. Your capacity to store glycogen increases as you increase your workload.

Water Weight and Fat Are Not the Same:

You might think that is an obvious statement, but if it were, there wouldn’t be so many people wondering why they’re working out but gaining weight. This water weight is a good weight. It is fuel within the muscles for high-intensity exercise. It is going to make your muscles look full and keep the cells hydrated so they can do their job efficiently.

It is so important that you get over the idea of weight during your weight loss program. You’d be better off calling it a fat loss program. That’s what you’re trying to do anyways, isn’t it? Weight fluctuates drastically even during a small window of time. Fat loss is a much more stable process.

Before you freak out and quit your fitness program over discouraging scale readings, remember that just because you gained weight, it doesn’t mean you didn’t lose fat. You have to measure fat if you want to know what is going on. If you do not measure your body fat, you’re navigating in the dark. Measuring your body fat will tell you how much of that weight gain was lean body mass and how much of it was fat. Your scale won’t do that.

Be prepared for a little weight gain at the beginning of your weight loss program, but understand where it’s coming from. Take before and after body measurements and have confidence that you are doing what you need to do to not only reach your weight loss goals but to be healthy both on the inside and out.  Remember this is a healthy lifestyle journey….



Looking for workouts and nutrition that work for life – not just another diet? Train virtually with the team from 1fw Training.  We offer daily, trainer written workouts for the home/gym – beginner to advanced, nutritional programs designed with your goals in mind, and so much more. 

Live like a fit person – for life!  



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4 thoughts on “Working Out But Gaining Weight, Why?

  1. What a timely topic for me! I’ve been dreaming out for about 10 days now. I’ve been on weight watchers for close to a year. I’ve had quite a but of success losing 100lbs. However, I wanted to be more fit so I joined a gym. I’ve been exercising regularly for about 6 wks and have really started to see a change in my body. In the last 2 weeks I’ve gained 10lbs and I couldn’t understand Why! My diet was still the same as when I was having the weight loss success. I figured I was just adding muscle and decided to reduce my food intake. Still wasn’t working so I backed off on the weight lifting for the last couple of days. I’m so close to my goal weight (I have 7 more pounds to lose) that losing the weight was more important. I would really like to achieve both. So this article gives me a little hope. I just have to be a little more patient and the weight will still come off! Once again thank you for a very timely article. Yours Truly, Mike Craig

  2. How often do we need to weigh on a scale and how often do we need to measure our bodies to understand our weight loss? How do we determine how much weight we should be losing per month to be on the healthy range?

  3. This. All of it, so timely for me. I’ve gone from mostly sedentary last year to training for a half marathon in 12 weeks. I just completed week 10 of 12 (the run is March 26). I’ve crosstrained 2x weekly (crossfit) and I’m logging miles using intervals (run 2 minutes/walk 30 seconds). My before and 6 week pictures show a difference but that scale hasn’t moved, not one lb. At 5’3, 47 years old, I gained 15 lbs from inactivity and decided it was time to get my life back. My dad passed in 2014 and I lost myself in the grief. I’m retraining my brain to accept that 125 lbs may not be in the cards for me anymore and that’s ok. This helps me better understand why the # on the scale isn’t doing what I thought it would. Thank you!

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