10 Common Causes of Unexpected Weight Gain

Today I wanted to talk about scale weight. Although we don’t advocate for measuring health progress only by the numbers on a scale, getting to the bottom of unexplained (and by that I mean unaccounted for) weight gain is still very important. These gains could serve as a possible indicator of underlying medical issues, worth further investigation with your GP. So here are 10 of the most common reasons why you may see unexplained scale weight increases:

1) Hidden calories in ‘health’ food

From Acai bowls, to smoothies, raw slices to paleo muesli…food trends and social platforms have definitely improved our palettes and the variety of real foods we choose to eat. However, that said, just because a meal is packed with nutrients doesn’t mean it gets a free pass when it comes to portions. Knowledge is power, and often these healthy foods are served very large in size and are super easy to over-consume.

An Acai bowl, full of yummy fruit, muesli, nuts and seeds can easily hit the 700 calorie mark. The same can go for large smoothies – and as they’re liquids, they leave the stomach quite quickly, meaning we feel we can fit more in (or we drink them alongside an actual meal as though they’re water). And raw slices, whilst packed full of healthy proteins and fats, are far more calorie dense than you may first think. 

2) Alcohol

Alcohol is often missed when tracking energy (calorie) intake. However, even small amounts of regular Alcohol are enough to contribute to weight gain (if not accounted for). With 125 calories in a single glass of wine, your daily drink could result in over 3 kg weight gain every 6 months. Here is a list of the calories in your favourite alcohol. 

3) Medication

Certain antidepressants, diabetes medications and antiseizure medications can cause weight gain. This is due to their effect on our hunger or metabolism or their influence over the way our body utilises energy. It is extremely important to keep on top of prescribed medications. However, if you are concerned that your medication is making weight management difficult, discuss this with your GP, who may be able to offer suitable alternatives.

4) Hormones

The endocrine system, which includes our adrenal glands, thyroid and ovaries, helps regulate hormones that control several functions in the body. One of these functions is our metabolism. Women experience a gradual decline in these hormones as they head into menopause. So like other medical conditions (i.e hypothyroid and PCOS) this can affect our metabolism, energy levels and weight gain.

5) Change of environment

Incidental exercise is a huge contributor to the amount of ‘energy’ burned each day. 

If you have recently changed jobs and find you’re sitting down more, or if you have moved house and you’re now driving to the shops instead of walking, your incidental exercise levels will have dropped. And this decrease in ‘incidental’ activity, over time, can be enough to stall weight loss efforts.

6) Food Intolerance 

Some food intolerances can cause constipation and bloating, both of which can leave us feeling heavier or less like our usual selves. Although food intolerance shouldn’t cause you to consistently gain weight, you may often see a superficial fluctuation on the scales. Gas, liquid or ‘contents’ in your bowel can sometimes weigh in excess of 3kgs.

7) Muscle gain 

Not all ‘weight gain’ is bad! Balanced nutrition and a progressive weight bearing exercise regimen usually results in an increase in muscle mass (which is what we are after). As muscle weighs more than fat, these ‘gains’ can show as an increase on the scales, despite decreasing body measurements. 

8) Fluid retention

Have you ever wondered how you can change weight on a scale so dramatically within 24 hours? Most of the time, this is simply due to changes in our body fluids. Our bodies can hold a huge amount of extra fluid in our tissues, blood, muscle, bladder and bowel. There are many different causes of fluid retention including dietary changes, increased salt in your diet, fluctuating hormones and medications. Addressing these causes should help. However, if you’re concerned it’s something more, we recommend discussing with your GP any other possible medical causes.

9) Too little sleep OR poor sleep patterns

Both a lack of sleep, caused by late nights and early mornings, and shift work (irregular sleep) take their toll on your body. The stress hormone ‘cortisol’ and hunger hormones ‘ghrelin’ and ‘leptin’ are just some of the major hormones impacted. This can cause an increase in hunger, food cravings and the potential for overeating. Being excessively tired also increases the likelihood of lethargy and missed workouts.

10) Quitting smoking 

We don’t advocate for cigarette smoking and thoroughly support those wanting to quit. There is, however, the possibility that small weight gain can be experienced during the quitting process. This is because the chemicals in cigarettes act as an appetite suppressant, as well as artificially increasing your metabolism. In stopping smoking, your body heals, foods start to taste better, your metabolism normalises, and hunger and your food intake can increase, potentially affecting your overall weight. 

As you can see, there is usually a reason for any unexplained weight gain. In solving your own weight gain, address the points in this list. If you’re still concerned, then see your GP to determine if there is an underlying medical issue.

Scale weight aside, regular exercise, rest and optimal nourishment is essential for long term health. To help establish healthy habits head to

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