Slow Metabolism: Why Some People Take Longer to Burn Fat

If you're trying to lose weight but can't manage to do so, the problem may be that you have a slow metabolism. We'll show you what it is and how to fix it.

Written and verified by el nutricionista Saúl Sánchez.

Last update: 29 June, 2023

Some people have a slow metabolism and, because of it, take longer to lose weight and burn fat. Their energy expenditure at rest is lower, which makes it more difficult to generate and maintain a deficit that allows lipids to be oxidized bit by bit. However, this doesn’t mean that it isn’t possible to achieve good weight loss results, simply that the process will take longer.

Before beginning, we must mention that metabolism is determined, in part, by genetics. Alterations determined by life habits can be experienced, but great changes will never be achieved overnight. From the point of view of genes, there’s still a great deal of ignorance, although, little by little, progress is being made that could give rise to effective pharmacological compounds against the problem.

Causes of slow metabolism

Genetics may be behind slow metabolism. However, there are many other factors involved. For example, if the thyroid isn’t working properly, the daily energy expenditure will be reduced. At the same time, many other symptoms will appear that can lead to a reduction in well-being. This is indicated by research published in The Journal of Clinical Endocrinology and Metabolism.

In these cases, the only possible solution has to do with the exogenous administration of thyroid hormones to compensate for the synthesis problems. Otherwise, people will feel fatigue and gain weight progressively, thus altering the state of health. The good news is that with a good medication regimen, the problem is efficiently avoided. Dietary strategies can even be considered to improve the results.

On the other hand, slow metabolism may be conditioned by a low amount of muscle mass. After all, lean tissue is the most metabolically active in the body. It consumes a large amount of energy and carries out exocrine and endocrine actions. For this reason, the development of sarcopenia must be prevented by all possible means, a pathology that causes muscle destruction and loss of strength.

One of the great keys in this regard is physical exercise. Through strength work, the synthesis of muscle proteins is stimulated, which is able to generate an anabolic environment. In addition, adjusting your diet will make a difference, and will satisfy the nutritional requirements on a daily basis.

As for protein, the needs are established at more than 1.4 grams per kilo of weight per day in people who do sports, according to a study published in the Journal of the International Society of Sports Nutrition.

How to reverse slow metabolism?

Reversing slow metabolism is a process that takes time. Beyond the possible genetic conditions, it’s crucial to place special emphasis on lifestyle habits to achieve good results. Of course, the changes take place little by little because processes such as hypertrophy aren’t achieved quickly. They’re modulated by constant activity and adaptations, within the framework of a sufficient nutritional intake.

Be that as it may, one of the key points when it comes to increasing metabolism is the gain in lean mass. For this, resistance work outs (strength training) must be prioritized. However, this can be difficult at first, as it isn’t uncommon for there also to be insulin resistance that negatively determines muscle adaptations and signals hypertrophy processes.

In general terms, it’s best to plan to do high-intensity work at least 3 times a week. The best thing will be to work at 6 or 12 repetitions and perform a total of 10 series per muscle group every 7 days. In this way, beginners will start to experience significant improvements.

Now, to get the most out of this routine, you will have to guarantee protein intake and a sufficient consumption of carbohydrates. The latter are the main energy substrates for carrying out strength work. Don’t go overboard with them in the early stages either, but training at high intensity in ketosis is usually not a good idea at first.

However, all this must be put into practice in the context of a hypocaloric regimen. You should always consume fewer calories than you expend. This will stimulate the mobilization of fats and begin to lose adipose tissue efficiently. In any case, in cases of very slow metabolism, this mechanism may take a while to occur, since it isn’t always feasible to generate this energy deficit.

Insulin resistance and slow metabolism

A parallel problem with slow metabolism is often insulin resistance. Normally, this is also caused by bad habits, beyond determining factors at the genetic level.

When simple sugars appear frequently in the diet, little by little prediabetes can develop, modulated by this mechanism that we’ve just discussed. This is indicated by research published in the journal Critical Reviews in Clinical Laboratory Sciences.

The result of this process is a greater difficulty for the body to efficiently choose the appropriate energy substrates for each situation. This translates into less lipid oxidation and less liver glycogen sparing. Not only do you experience worse sports performance, but fat accumulates at a visceral and subcutaneous level much more easily, worsening your state of health.

As with a slow metabolism, insulin sensitivity can increase over the years. Above all, a change in habits is needed to achieve a significant improvement.

The key is again the gain of lean tissue. However, under this scenario, it can be a bit more complicated, especially at first. Insulin is the main anabolic hormone in the body, and if it isn’t kept at correct levels, it will be difficult for it to perform its function.

Now, to improve the results, it’s best to ensure a high volume of physical work at a high intensity. Gradually the sensitivity of the hormone will increase and the nutritional deposits will begin to be used more efficiently. Likewise, there are options that can speed up the process, such as caffeine consumption. This is one of the ergogenic aids that has shown the greatest benefits.

Supplements against slow metabolism

It’s important to mention that some supplements improve the problem of slow metabolism, as long as it isn’t conditioned by serious genetic alterations or hypothyroidism. The idea would be to increase energy expenditure at rest. However, everything that manages to improve insulin sensitivity will also cause positive changes in the state of body composition.

One of the best options to increase metabolism is by eating spicy food. Foods with this flavor have a substance inside, called capsaicin, which slightly increases body temperature, causing greater energy expenditure. In this way, weight loss is also promoted over the weeks, as evidenced by research published in the International Journal of Food Sciences and Nutrition.

Another supplement that also works efficiently is creatine. It doesn’t have a direct effect on energy expenditure, but it does improve training performance significantly. Thanks to this, key processes such as muscle hypertrophy will be promoted. As a result, the amount of energy used at rest will increase, which, in turn, will cause a reduction in adipose tissue.

Of course, when using creatine it’s important to take into account that an increase of one kilo in body weight will be experienced. This is due to an accumulation of water at the intracellular level. However, once you stop taking it, you return to your usual weight.

In addition, the strength benefits more than make up for the slightly increased body weight. Its supplementation is almost always recommended, especially in sports contexts.

The link between sleep and slow metabolism

Finally, we have to address the problem of lack of sleep and its effects on metabolism, which can slow it down in the medium term. During the night there are many mechanisms that have to do with recovery and with the maintenance of homeostasis in the internal environment. If at least 7 or 8 quality hours of sleep aren’t achieved each night, the hormonal environment may be altered.

According to a study published in the journal Metabolism, breaking circadian rhythms through sleep problems would cause alterations in metabolism. There’ll start to be an inefficient use of nutrients, and, over the months you may experience weight gain due to lower energy expenditure. For this reason, good daily habits must be ensured.

To get a good night’s sleep, it’s essential to try to get to bed early, and avoid exposing yourself to the light of mobile devices just before going to bed. Otherwise, the synthesis of melatonin in the internal environment, the hormone that regulates sleep and wake cycles, would be suppressed. On the other hand, it’ll be decisive to always try to go to bed at the same time, more or less.

If it’s difficult for you to get to sleep, you can always choose to include a supplement in your diet, such as melatonin itself. This will make it easier to sleep and you’ll be less likely to experience sleep interruptions.

Doses of no more than 2 milligrams per day are used, although higher concentrations have shown benefits at the antioxidant level.

Slow metabolism, a problem with a medium-term solution

Slow metabolism is a problem that can be solved over the months, although it takes perseverance and discipline. In most cases, the key lies in a change in habits – promoting the regular practice of physical exercise and changing your diet. Supplements can also help, although miracles shouldn’t be expected; they’re just the icing on the cake.

Lastly, keep in mind that if you don’t achieve good results, even if you change habits and are consistent, then perhaps it’s best to consult a specialist. There may be a basic pathology that must be corrected by means of some type of medication.

The most typical example is when the thyroid starts to function differently, but other diseases and conditions can affect it as well. An accurate diagnosis and appropriate intervention will always be needed.