Metabolism and weight loss. Why is it so hard to slim down?

The real reasons behind “slow metabolism”

The concept of “slow metabolism” is often overused, while in most cases weight loss problems are not a result of dysregulation, but stem from much simpler things, such as an underestimated calorie intake, overestimated amounts of physical activity, faulty measurement methods or an improperly calculated calorie deficit. In some cases, unsuccessful weight reduction may indeed be caused by metabolic reasons – you might want to look into the following possible culprits:

Metabolic adaptation, or metabolism in survival mode

Metabolic adaptation is sometimes referred to as “metabolic damage” or even “metabolic collapse”. It consists in the body becoming adapted to a scarcity of calories on a weight reduction diet. After being on a negative energy balance diet for a while, your body will “get accustomed” to the reduced calorie intake and will adjust, minimizing energy use. This is a natural protective mechanism against further body mass loss and a strategy for the body to recover the lost pounds. Metabolic adaptation most often happens following significant weight loss or during a prolonged period of dieting.

It is often the metabolic adaptation mechanism that is to blame for the unsatisfactory results of a reduction diet, even if the overall energy balance is negative. This happens because the body grows accustomed to the calorie deficit and starts to optimize its energy expenditure. The direct causes of this process include:

• limited activity of brown fat,
• hormonal dysregulation and low levels of leptin, insulin, testosterone and T3 hormones,
• enhanced energy production efficiency in the mitochondria,
• elevated levels of ghrelin, which increases the drive to eat.

These metabolic modifications result in poorer thermogenesis, less spontaneous non-exercise activity due to fatigue and low motivation to continue dieting. Metabolic adaptation is a fact and can amount to even 500 kcal per day. This means that the basal metabolic rate is reduced by a maximum of 500 kcal as a result of prolonged dieting. Most often, however, the effect is weaker, ranging between 150 and 300 kcals.

Interestingly, metabolic adaptation applies to the additional reduction in the basal metabolic rate resulting from a low-calorie diet and does not just represent reduced demand due to weight loss.

Hypothyroidism and slower metabolism

Hypothyroidism is a condition which can genuinely derail all weight reduction efforts. Increasing weight is one of its symptoms. Hypothyroidism may reduce energy expenditure by up to 30% per day. T3 and T4 hormone deficiency, coupled with increased TSH levels, leads to a lower basal metabolic rate, but also produces additional symptoms, which in turn lead to decreased non-exercise activity thermogenesis.

Individuals with hypothyroidism may feel drowsy, apathetic, listless and be less tolerant to cold temperatures, while all of these symptoms reduce their inclination to engage in activities that burn calories. Skipped workouts, passive leisure and lack of motivation or energy to take up additional activities all lead to significantly less exercise and fewer calories burnt. This is bound to affect the metabolic rate. Proper treatment and dosage of medications can limit this undesirable result of hypothyroidism and bring metabolism back to normal.

“Disturbed” metabolism following low-calorie diets

If you have been dieting “forever” and experimented with innumerable alternative methods to help you shed some pounds, with varying degrees of success, think that all those low-calorie diets might actually have contributed to the decline in your metabolism. Fasting may well have the most pernicious effect, along with extremely low-calorie eating plans, which recommend a calorie intake below the level of the basal metabolic rate, as well as low protein diets.

While occasionally effective in reducing body weight, such methods often come with the undesirable side effect of muscle loss. This, in turn, directly lowers the basal metabolic rate. When this happens, it is natural that your body will need less energy to sustain its internal processes and this is literally what “decreased” or “slow” metabolism means. The way out is to switch to a balanced diet with a calorie intake close to the body’s total energy demand, as well as to attempt to build up more muscle or recompose the body. More muscle always means a higher resting metabolic rate.

What factors have a real effect on metabolic processes? Can slow metabolism be “fixed”?

Now you know that you can actually directly tweak many factors associated with the so-called “speed” of your metabolism. If you really want to “repair” your metabolism and turn it up a notch, there are some things you can try. Here are some strategies for you to ramp up your daily calorie burn.

1. Create opportunities to boost your NEAT

You have already learned that non-exercise activity thermogenesis (NEAT) is an extremely important contributor to your overall metabolism. Create opportunities for your body to naturally burn more calories: take the stairs instead of the lift, get off the bus one stop early, take a walk during your work break... Even the busiest person can find some ways to boost their NEAT.

2. Try a diet break

If you have been dieting for a long time and suspect you might be suffering from metabolic adaptation, try a diet break. Try to replace your reduction diet with a “caloric balance” plan (where calorie intake matches the calorie expenditure) for a week or two in order to maintain your current body weight. This strategy will prevent muscle tissue breakdown, while it may also restore hormonal balance (e.g. improve sensitivity to leptin and thyroxin) and enhance your motivation to continue on a reduction diet. A diet break is not indispensable in the weight reduction process, but many weight-watchers have reported positive outcomes with such a strategy. Use it especially when you feel tired of all the slimming efforts, if you notice that it is getting more difficult for you to lose weight or if you enter a more stressful or hectic period in your life.

3. Manage muscle mass

The muscles naturally consume a lot of energy. Your body burns more calories to sustain muscle cells. Individuals with more muscle mass have an increased basal metabolic rate, even when they are not actively exercising. Keep building your body, make your workouts more varied by adding some strength exercises and avoid strict low-calorie diets which trigger muscle breakdown. This is the best strategy to kickstart your metabolism.

4. Choose a balanced diet plan to match your lifestyle

Make sure your diet meets your needs. Do not be swayed by the calorie or macronutrient content of your friends’ menus. The fact that a particular nutrition plan “works” for them, does not mean it will do the same for you. Calculate your individual calorie demand, adjust the protein amount to your objectives and ensure an adequate supply of vitamins and minerals, i.e. the molecules essential for the various metabolic reactions taking place in your body.

Read also: “7 Products That Speed up Your Metabolism”.

5. Sleep well

There is conclusive evidence to confirm that lack of quality sleep is a major risk factor for obesity. Sleep deprivation increases the release of the stress hormone cortisol, it affects the levels of hunger hormones ghrelin and leptin and inhibits muscle regeneration and rebuilding. All of this can lead to a lower basal metabolic rate and thus – to “slow metabolism”. Regularly getting sufficient amounts of quality sleep is essential for the smooth functioning of various metabolic processes in the body and supports overall fitness.

6. Check for health conditions and disorders

If you suspect you might be experiencing some hormonal issues (hypothyroidism, insulin resistance or PCOS), or other conditions which might affect your weight, see your doctor. Once you are properly diagnosed, you will have a better understanding of your own body and you will know how to adjust your strategies to meet its needs and requirements. A one-size-fits-all approach is rarely effective.

Does your metabolism become sluggish with age?

Have you ever heard people say that metabolism naturally slows down after you hit 30/40/50? That’s not entirely true. Some data did actually suggest that the metabolic rate may decrease by ca. 100 kcals per each decade of life, but this has not been confirmed by latest research.

It turns out that the daily energy expenditure is relatively stable between the 20th and 60th year of life and depends largely on lean body mass (the amount of muscle mass, as discussed above). Metabolism only slows down in people aged over 60, but even then it is only by a mere 0.7% per year. This means that for an individual with a basal metabolic rate (BMR) of 1500 kcals on their 60th birthday, the BMR will only decrease by ca. 10 kcals per year. It will amount to 1490 kcals one year later and on their 70th birthday it will stand at 1420 kcals.

However, it is true that people gain weight as they age. Why is that? It is not a problem of “metabolic dysregulation”, but of changing lifestyles and habits. A sedentary lifestyle, driving instead of walking or taking the bus, less time or motivation to engage in physical activity... Reduced energy expenditure decreases the overall metabolic rate, which does not mean you can blame some mythical “metabolic processes” occurring in your body as you age for your expanding girth. This excuse can only be used by people aged 60+ and even then only to a limited extent.

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