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7 Reasons For That Pesky, Unexplainable Weight Gain

unexplainable weight gain

Unexplainable weight gain can be one of the most frustrating things that can happen on a weight loss journey. It’s also one of the biggest reasons why people give up on losing weight.

I’ll summarize some of the most common reasons below. These reasons may help you properly reflect on your own unique challenges around unexplained weight gain.

Remember, an unexplainable weight gain is NOT a sign that your body is destined to never lose weight. Taken from a different perspective, these gains can actually be a good thing. They are an opportunity to further develop your skill of weight loss and better understand your body. Improving this skill will help your self-awareness, which then enables you to fix your damaged feedback loop.

Reason #1: Increased Physical Activity

unexplainable weight gain - exercise

Did you know that increased exercise makes you retain an immense amount of water weight? This water weight can be upwards of 3-4 pounds. It can continue to increase for 3-4 weeks while your body gets used increased physical activity! Here are some references (123).

This water weight increase is actually very good for you! It’s because you’re storing more glycogen, which is powerful energy for your muscles. You WANT this type of weight gain, as it gives you more energy and makes you stronger, unlike fat.

There’s a sad but very common scenario that happens often. A person gets inspired to lose and starts to exercise. Unfortunately due to this glycogen water retention, they observe no progress on the scale. They then quit, even though in 3-4 weeks the glycogen weight increase would have stabilized. They would have started to see all of their good habits show on the scale.

If you have unexplainable weight gain but you’ve increased your physical activity recently, it’s almost a certainty a portion of that weight gain is due to glycogen. If you are genuinely still eating at a caloric deficit, your weight will likely continue back on its downward trend.

There is another reason that increased physical activity can cause weight gain, however: people often get hungrier and eat more when exercising. This can often be completely subliminal. I can easily gain weight if I don’t keep an eye on my weight when I begin a new exercise routine.

Here’s a more detailed article about how it is totally normal to gain weight when starting exercise.

I’d recommend shifting your goal date out a month if you start exercising and see this happening. Doing so will reduce the odds of discouragement. Sticking with the process is more important than achieving a number on a certain date.

Reason #2: Subtle Dietary Adjustments

unexplainable weight gain - diet

There’s something about pasta that triggers my body. I gain 2+ pounds on the scale the next day when I eat it. Although this does not happen to everybody, refined carbohydrates are notorious for making people retain an immense amount of water.

There often seems to be trigger foods that certain people have that cause their bodies to react. The better we can understand what these trigger foods are, the better we can recognize what’s going to happen to our weight when we eat these foods.

Another example: I had a friend that whenever she hit a plateau on her weight loss journey, would try to double down on caloric reduction, drinking diet sodas instead of caloric juices. What she didn’t understand was that diet sodas caused her to bloat immensely. She would gain (temporary water) weight even though she was actually on a caloric deficit and get incredibly frustrated. When she discovered this connection, it was like a Eureka Moment for her. She stopped drinking diet soda, which helped stabilize her weight fluctuations and reduced her frustrations around weight loss significantly.

The opposite can also be true: if you change your diet, your water retention may shift downwards! You might think that this new diet is the most amazing thing on earth. Eventually, the water weight will stabilize and you may wonder why you are no longer losing weight at same rate.

If you are gaining weight for an unexplainable reason, reflect on if you have done anything different with your diet. Even small changes can cause variations in water weight that impact your weight.

Reason #3: Your Scale Is Off

unexplained weight gain - scale

The scale lies, but sometimes the scale REALLY lies. If the scale is broken or off-calibration, the numbers may be completely different than a week ago.

If you buy a new scale, be aware that the numbers may not exactly match the previous scale. Additionally, if you regularly move your scale around or it’s an old one that doesn’t calibrate itself well, the number could be off.

If there has been a recent unexplainable weight gain, reflect on if you have moved the scale to a different location, or if you may have damaged the scale somehow. If you use another scale and the numbers are significantly different, one of the scales is off. It may be worth adjusting your start weight on your goal to match the difference between the two scales.

It can feel discouraging if you realize you’re actually a higher weight than you thought you were due to scale mis-calibration. Remember that the trend is so much more important than the actual number on the scale. You haven’t actually changed and as long as your trend keeps going in the right direction you will succeed.

Reason #4: You’re Being Inconsistent With Your Weigh-Ins

Similar to the reason above, if you weigh yourself with different scales regularly or in different places, or at different times, or with different clothes, the numbers will flucutate like crazy. Try to weigh yourself at the same place at the same time with the same scale, optimally right in the morning after you go to the bathroom.

Reason #5: Physiological/Hormonal Changes

Particularly for women, the onset of a period can cause immense water retention or bloat. If this happens at the same time every month, then it is important to recognize that once the hormones change back to your normal state, the water weight will go off. Hormonal changes in men can also cause water retention, and things like stress can also cause hormonal changes.

If there has been a recent unexplainable weight gain, reflect on if there have been changes in your life that may have caused hormonal changes. Stress, dietary changes, or health issues can cause hormonal changes. Although rare, health issues like cancer can cause hormonal shifts which then can cause rapid weight gain or weight loss. Speak with a doctor if all of these other issues don’t seem to apply to your situation and you are experiencing rapid weight gain or weight loss.

Reason #6: You’re Not Sh*tting

I bring this up because it can actually be a big reason why the scale doesn’t move, but people often are unaware of this. The amount of stool we have in our bodies can get up to 3-5 pounds. If you haven’t pooped in a while, this may be the reason the number on the scale is higher than expected. Once you poop, you’ll lose the weight.

Reason #7: You’re Actually Eating Too Much

There is also a very common reason why this could be happening: fat gain due to eating more calories than you are using. If this obviously the case in your situation, then good—the obvious next step is to get back into a caloric deficit. I say this is good because knowing why you are gaining weight is immensely valuable. Knowing allows you to reflect and then search for a solution.

Many of us who try to lose weight may be denying that we are doing this. It’s very possible that we are right: the 6 reasons above are some of the reasons where the number on the scale can go up even though we are in a caloric deficit.

Unfortunately it’s also extremely easy to lie to ourselves. I was regularly guilty of doing this in the past.

There’s a British reality television show called Secret Eaters (episodes are on YouTube if you are interested in watching). The show tracks people who are looking to lose weight with cameras following them around. At the end of the week, people are shown a list of all the food and drink that they have consumed. Without fail, the people are shocked, refuse to believe the calorie counts, and deny that they’ve eaten that much. They are then shown the video footage where they have eaten 1000 calories of snacks between meals, or drank a few glasses of wine each night, proving to them that they are consuming many more calories than they have estimated.

We chuckle at the characters at the show, laughing at how delusional they could be. However, many of us are delusional too when it comes to how much we actually eat! Humans will mindlessly eat if food is around. If you have a snack drawer at work or pantry somewhere you can test this for yourself. Lock the drawer or door and see how often you walk to the pantry or try to open the drawer. I did this at work one week to test myself and I found myself unconsciously trying to open my snack drawer regularly!

This should actually be expected. Eating less than your body needs to maintain its weight is not natural at all! Think about it from an evolutionary standpoint. Humans who would naturally eat less than they need to on a regular basis would have greater odds of dying out, replaced by those that naturally consume enough calories to actually survive. To lose weight, being actively conscious of our eating habits is often required.

Does this mean that trying to lose weight is a pointless uphill battle? Absolutely not. It just means that a conscientiousness about eating is beneficial. One thing that I recommend for people that struggle to understand why they gain weight even though they feel like they are doing everything right is to take pictures of everything they eat throughout the day, no matter how small. Doing this can increase the conscientiousness of eating, which can reduce this risk of unconscious eating.

What’s The Reason For Unexplainable Weight Gain? Reflect!

unexplained weight loss - why?

I list many reasons above that explain unexplainable weight gain, but everybody’s weight loss journey is different and it could be something else. Reflect on the past week and see if there have been any subtle differences between the last week and prior times where you were losing weight successfully. Think back on when you were doing really well on weight loss and try to replicate that.

What’s important is that you don’t let unexplainable weight gain interfere with your weight loss journey! Don’t let it discourage you. As mentioned above, it can be an opportunity to learn.

The more you understand how your body works and how your mind and body reacts to certain foods, the more you can start understanding the reasons behind every weight gain and weight loss that happens. And the more you understand, the more you fix your feedback loop and the more you shift right on the weight control spectrum. At the beginning of my weight loss journey I often didn’t fully understand why my weight went up or down. Now however, I have a solid understanding about why my weight goes up or down.

As always, your weight loss journey is unique. Although there are a lot of common truths around weight loss, everybody has different challenges and the person that actually has the most important information to discover the solution is you. Using Luuze helps you make regular reflections, asking you the right questions at the right times so you improve your skill of weight loss and repair your feedback loop, losing weight for good.

2 thoughts on “7 Reasons For That Pesky, Unexplainable Weight Gain”

  1. Such a great reminder. I find my weight loss is going: down, steady, up, down a bit more, steady, up, down a bit more… you get the idea. I think of the saying two steps forward one step back. It’s kind of like that, but is still going down every week, so I’m happy with that.

    Thanks for the encouragement!

    1. For sure! And even if it’s 10 steps back it’s okay, as long as we reflect on the experience so we can grow. If we do this we’ll be able to take 11 steps the next time.

      Great work on your progress! Love hearing your updates!

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