MS, Registered Dietitian, Former President of CT Academy of Nutrition & Dietetics
Table of Contents
If you started dieting and exercising daily to lose weight, but have seen no results, you might wonder, “why am I not losing weight despite being on a calorie deficit?”
In this article, we address how a calorie deficit works, how fast you should expect to lose weight, and why your calorie deficit may not work as it should.
Many people believe that exercising or dieting is already enough to achieve fat loss. However, this is not true if a calorie deficit is not achieved.
A “calorie deficit” refers to eating less than our dietary requirements so that our body is forced to use our stored fat to generate energy. And this is the main requirement for weight loss.
Sleep can also impact the fat-loss process. A lack of sleep can result in stress and increased cortisol secretion, which can affect how fat is metabolized [1] [2]. Poor sleep can also increase food cravings, making it harder to stay within a calorie deficit [3].
However, the most important factor in losing weight is your calorie intake. A calorie deficit can be achieved by simply eating less than your maintenance requirements. This can be achieved through a modest reduction in calorie intake, increased physical activity, or a combination of both.
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Being in a calorie deficit is not unhealthy, as long as the deficit is calculated appropriately.
A safe and sustainable calorie deficit should be around 10-20% less than your maintenance calories to prevent lean muscle loss [4] [5].
Some more extreme deficits, on the other hand, such as a 600-calorie diet, can make you lose weight faster. However, they can harm your health. Cutting your calories too low can lead to fatigue, muscle mass loss, hormonal imbalances, decreased bone density, and increased cortisol levels [1] [2].
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Depending on how much weight you need to lose, it can take more or less time to get rid of the excess fat.
In a healthy calorie deficit, you should aim to lose between 0.5 and 1kg per week, which means it can take around 70-140 days to drop 10kg, depending on your average weekly loss.
All in all, you can expect to start seeing visible results after sustaining a calorie deficit for at least 4 weeks [2] [6].
It is important to note that women tend to take longer to shed fat than men due to hormonal reasons, as well as the natural levels of females’ essential fat stores. Women, in fact, physiologically require more fat in their bodies to maintain a well-balanced hormonal system [7] [8].
If you got to a point where you’re starting to wonder, “why is my calorie deficit not working, even if I eat less and less”, then there might be other factors influencing your weight loss. Below we discuss the main ones.
If you are not losing weight on a low-calorie diet, or worse, experiencing weight gain despite being on a calorie deficit, then pay attention to these two possible reasons:
A calorie deficit is calculated on one’s body weight. Therefore, the starting calorie deficit might turn into a maintenance calorie level as you start weighing less. Because of this, your calorie deficit needs recalculating every so often in your weight loss journey so to reflect your current weight and dietary needs.
Many people cut calories but are not focusing on the type of calories they’re consuming. For example, if you consume a diet low in protein and high in sugar and fats, this may prevent you from losing weight even if you are in a calorie deficit.
Despite the concept “a calorie is a calorie” being correct, it is also true that the source of such calorie has a major impact on how that food is processed by the body and its effect on our body composition [9].
Overconsumption of alcohol can also lead to an excessive intake of calories and sugar from the alcohol itself and the type of food commonly eaten along with it.
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Sleeping too little can lead to increased stress levels, which can raise levels of the stress hormone cortisol. This hormone is responsible for increased fat storage, the breakdown of muscle tissue and the consequent decrease in basal metabolic rate [10].
A decrease in metabolic rate means that your body requires fewer calories to survive, meaning that what used to be a calorie deficit before may eventually become a calorie balance, hindering your weight loss.
Some health conditions may be the reason why you are in a calorie deficit and not losing any weight.
These mainly include hormonal imbalances such as hypothyroidism, illnesses that affect insulin response and glucose metabolism, such as diabetes, or a mix of the two. An example of a mix of these two imbalances is the case of polycystic ovary syndrome [11] [12].
Some medications such as antipsychotics, antidepressants, diabetes and non-alcoholic fatty liver disease medications, hormonal therapies, and corticosteroids can inhibit weight loss and actually promote fat accumulation [13] [14] [15] [16].
Water retention can be a reason why your weight is not decreasing on the scale, even if your body composition is changing.
It can be caused by a series of factors, such as having a diet rich in salt, using certain medications, hormonal imbalances, and some health conditions like the abovementioned hypothyroidism [17] [18].
If you work out a lot, especially if you lift weights, your weight may not be changing due to an increase in muscle mass, which can result in either your body weight staying the same or, in some cases, increasing [9].
If you are already cutting your calories low and still not losing weight, then it might be that you have very high expectations about weight loss time frames.
An ideal and healthy weight loss should occur at a weekly rate of 0.5-1kg, although the first few weeks can result in a greater loss of weight if someone is particularly overweight.
If you train most days of the week and eat well, you may be confused if you don’t see a drop in weight on the scales, and may wonder: “why am I gaining weight on a calorie deficit even if I exercise?”.
Not losing weight despite being on a calorie deficit and partaking in exercise daily can be a sign of body recomposition.
This means that the weight is not changing, but the components of your body are, indicating that you are losing body fat but also building muscle at the same time.
A body recomposition can occur at small deficits, such as the 10-20% range indicated earlier, at calorie balance, or even at a slight surplus, as long as protein intake is kept high [9].
Body recomposition is generally considered a more positive outcome than a usual weight loss. That’s because you also gain muscle and develop strength and endurance, which influence your health positively in the long run. This is why it’s important (and motivating) to not solely focus on the scale but also on your strength, how your clothes fit, and how much muscle you are gaining.
If you struggle to follow separate diet and exercise plans, using an all-in-one weight loss app can help you keep track of both your nutrition and exercise habits in one place.
A nutritionist can help you lose weight by advising on healthier food choices, meal planning, emotional eating strategies, and so on. A nutrition professional can also calculate your calorie deficit correctly, based on your specific needs, as well as prevent any dietary deficiencies.
It is particularly important to consult your healthcare provider or a dietitian if you suffer from any chronic condition, such as PCOS and diabetes, are pregnant, or have a fairly high BMI.
Being in a calorie deficit doesn’t necessarily mean you are going to lose all the excess weight. Below you can find the key points about calorie deficits and weight loss:
This article is intended for general informational purposes only and does not address individual circumstances. It is not a substitute for professional advice or help and should not be relied on to make decisions of any kind. Any action you take upon the information presented in this article is strictly at your own risk and responsibility!