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Why do I gain weight when I eat 1200 calories

It's a common question among women who are trying to lose weight: why do I gain weight when I eat 1200 calories? The answer, unfortunately, is not always simple. There are a number of factors which maybe masking weight loss, even when eating a relatively small amount of calories. Here's a look at some of the most common reasons why you might be seeing the scale go up instead of down.

1. You may be eating more than you think - keep track of everything you eat and drink in a day

When it comes to tracking what we're putting into our bodies, research shows us how it's so easy to underestimate just how much we're eating and drinking in a day. To truly understand where your nutritional intake is coming from, tracking correctly is one of the most powerful tools to understand how much you're currently eating and to make better dietary decisions. Keeping track of everything we eat and drink can help us stay on top of our diet, improve our overall health and create accountability for the nutritional choices that we make each day. This only needs to be a temporary measure, tracking should not be something you do forever, but be used to help you become more intuitive with your eating.

2. Scale weight is masking fat loss

It is important to recognise this disconnect between scale weight and actual fat loss when planning a weight loss programme. Scale fluctuates can come from many things other than fat loss such as fluid changes, menstrual cycle, sodium and carbohydrate intake. So it is important to recognise that the scale will fluctuate throughout the week even though you're still using fat. This is why at Box Nutrition we look at trend lines over the week/month to understand if fat loss is really occurring.

3. You're not being patient enough to see your weight loss goals

It can be discouraging when we don't see results as quickly as we would like, or if you hit a plateau. However, patience is key when it comes to weight loss. It can be easy to chase quick fixes and be hard on ourselves for not seeing the desired results. To help overcome this is it is important to set yourselves realistic weight loss targets.

As a rule of thumb, you should sim to lose 0.5-1% of your bodyweight each week, however, this will depend on your starting weight and composition. At Box, we aim for between 5-10lbs per month of weight loss with Ignite. You will lose weight more quickly than this with FAD diets, however you're it's almost certain to put the weight back on.

With Ignite, we aim for 0.5-1% of weight loss per week which might not be as quick as a FAD diet in the short term, however it leads to sustainable long term change.

4. You're not losing weight because you're eating back the calories from exercise

Eating back the calories you've burned through exercise can put a serious damper on your weight-loss efforts. Studies (1) have shown that people got to the gym can often overestimate the calories they have burned by up to 70%. Other studies (2) Unsurprisingly, research has demonstrated that people consume more calories than they expend because their brains send them the message that they "deserve" it. Even when you track your workouts, research (3) has shown trackers can be off by up to 40%, which is a lot!

6. You're not losing weight on 1200 calories because of metabolic adaptation

Many people struggle to lose weight even when they maintain a consistent 1200 calorie diet. The reason why this may be happening is due to metabolic adaptation. This is a term used to describe the bodies natural tendency to decrease its metabolism Rate of Metabolism (RMR) in response to caloric restriction, leading to slower fat loss than expected. In addition, as metabolism slows, each calorie consumed yields less energy, resulting in inadequate sustenance for an individual’s body composition and health needs. To combat metabolic adaptation and achieve effective weight loss, it is important for individuals to increase activity levels and cycle calories appropriately.

7. You might be struggling to lose weight on 1200 calories because your metabolism is slow

Losing weight can be a difficult task, especially if your metabolism is running slow. It's possible that with only a 1200 calorie diet, it might not be enough to shed off those extra pounds due to metabolism costs. Metabolism costs are when your body uses more energy than you consume in food, meaning your metabolism speed has decreased. To understand if you have a slow metabolism then the only way to know is through a Resting Metabolic Rate (RMR) test.


If you're not losing weight despite following a 1200 calorie diet, it could be for any number of reasons. You might be underestimating how many calories you consume, the scale might be masking fat loss or you could be eating the calories you burn from exercise. It's also important to consider that weight loss takes time and patience - if you give up too soon, you'll never see results. If all this sounds familiar then get in touch at , so we can help identify where you might be going wrong and offer some solutions.


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