Five Reasons Why Undereating Is Not The Answer

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Sean Wilson

Sean Wilson

Many people resort to undereating to get in shape, but the reality is that this is one of the worst things you can do. Here's why.

When trying to get in shape, one of the first actions people take is to drastically reduce their calorie intake, due to the belief that the less you eat, the more fat you will lose.

However, as the weeks pass by, the process becomes more and more challenging and weeks of over-restriction with nutrition lead to a blow out, usually on a weekend or at social events. As a result, any progress is halted and things go around in cycles.

So, why is undereating not the solution? How can it have a negative impact on your life?

Stalls Fat Loss

The first thing you need to sort out is your nutrition. Eating too few calories is ineffective and dangerous because it will drastically slow down your metabolism (the range of biochemical processes that occur within your body to break down food into energy) and soon put a halt to the fat-burning process. Therefore, all your hard work in the gym and supposed ‘discipline’ with your nutrition will be for nothing.

So, while it is essential to be in a calorie deficit, that deficit has to be moderate and not extreme, which is usually 400-600 calories below your maintenance level (the calories you need to consume to stay the same weight and look the same, based on your height, weight, amount of muscle tissue and activity levels). By doing this, you will enable your metabolism to function properly and lose body fat more consistently, as well as keep your energy levels to a relatively high level.

Low Energy

Another huge part of increasing your energy levels will be your diet. This will be vital, not only in achieving your goals, but also fuelling your workouts and remaining full of energy throughout the day. It is vital that you have a diet that features a good balance of protein, carbohydrates, vegetables and, to a lesser extent, fats to support you.

Consuming plenty of carbohydrates, in particular, is going to be important because it is going to be your primary source of energy throughout the day. Aim for carbohydrates that release energy slowly, such as oatmeal, rice, potatoes, pasta and bread, so that you avoid sharp spikes and dips in your blood sugar levels and that your energy levels remain consistent. Fruit is also a good, healthy option if you are looking for a sharper energy hit. Do not neglect carbohydrates from your diet, especially if you want to have balanced, high energy levels.

Risk Of Losing Muscle Tissue

Another area that very low calories can affect is your muscle mass. Not only will it stall muscle growth, but it has also been shown to cause muscle loss, especially if there is very limited protein in the diet. Many people lose a lot of weight on extreme diets but end up unhappy with their body shape, simply because part of that weight loss is muscle tissue.

So, to add muscle and improve your body shape, you must eat more, especially when it comes to protein and carbohydrates. To combine this with fat loss, your calorie deficit must be moderate, meaning that eating not enough calories will have an adverse effect on what you are trying to achieve.

Low Strength

By decreasing your calories, you may also mind that your strength levels take a hit, which will have an adverse effect on progressing in this area in the gym. Unlike cardio, which is something that can be performed in a fasted state without a huge dip in performance (depending on what you are doing), resistance training is something that requires plenty of energy beforehand.

So, on training days, you must fuel yourself properly. This means having a good balance of protein and carbohydrates in your diet, along with a smaller portion of fats. If your session is in the morning, it is advisable to include carbohydrates in your prior evening meal, so that you have energy that can carry across to the next day. On non-training days, the need for more food will be lower, so dropping your calories slightly, based on your output can be advantageous. This is what is known as ‘calorie cycling’.

Health Consequences

As well as helping you to lose weight or body fat, healthy carbohydrates have plenty of other benefits to your body. The combination of resistant starch and fibre can improve digestive health, along with keeping your blood cholesterol levels in check by playing a role in lowering ‘bad’ low-density lipoprotein (LDL) cholesterol. Carbohydrates can also help you maintain a sharper memory and improve or maintain a healthy mood and lifestyle. Finally, certain carbohydrate sources, such as oatmeal, contain vital antioxidants, which play a huge role in fighting off free radicals in the body that can lead to harmful diseases.

So, in summary, carbohydrates are not bad for you. They are necessary to provide energy for your day, sustainability for your diet, and improve or maintain other important areas, such as sleep and overall health. The way to lose weight or body fat is through being in a consistent calorie deficit for a significant period of time, regardless of whether you have carbs or not. This is the most important point.

But if you want to be consistent during your weight loss or fat loss journey, including carbohydrates in your diet is going to improve your chances of sticking to your diet and therefore making great progress over time.


So, while undereating is a common tactic people turn to when trying to get in shape, it is in fact one of the worst things you can do. This is because it stalls fat loss by slowing down your metabolism, decreases energy levels, risks loss of muscle tissue, decreases strength, and has negative impacts on your health.

While you must be in control of your calories to lose fat and change your body shape, it is also important to understand that eating more will have a much more positive effect on your life, goals, and performance during the day. Don’t make the mistake of undereating.

Photo Credit: Envato Elements

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