Is Your Metabolism Really “Slow” – Or Is Something Else Going On?
“I have a slow metabolism.” It is one of the most common complaints I hear at our practice in Zürich Seefeld. And while the concept of a “slow metabolism” is often oversimplified, there is truth behind the frustration. Your metabolic rate – the speed at which your body converts food into energy – is influenced by multiple factors, many of which are modifiable.
What Determines Metabolic Rate?
Basal Metabolic Rate (BMR): The energy your body uses at rest for basic functions – breathing, circulation, cell repair. This accounts for 60-75% of total daily energy expenditure and is determined by body composition, age, sex, genetics, and hormonal status.
Thermic Effect of Food (TEF): The energy used to digest and process food, accounting for about 10% of energy expenditure. Protein has the highest thermic effect (20-30%), followed by carbohydrates (5-10%), then fat (0-3%).
Physical Activity: Both structured exercise and Non-Exercise Activity Thermogenesis (NEAT) – fidgeting, walking, standing, daily movement – make up the remaining 15-30%.
Medical Causes of a Genuinely Slow Metabolism
Hypothyroidism: Your thyroid gland is the master regulator of metabolic rate. Even subclinical hypothyroidism can reduce metabolic rate by 10-15%, resulting in weight gain and fatigue.
Metabolic adaptation from dieting: Repeated calorie restriction teaches your body to be more efficient, reducing thyroid output, leptin levels, and spontaneous activity. This is real and measurable.
Low muscle mass: Muscle is metabolically expensive tissue – it burns calories at rest. Loss of muscle mass (from ageing, inactivity, or crash dieting) directly reduces metabolic rate.
Hormonal changes: Declining testosterone, growth hormone, and oestrogen all reduce metabolic rate with age. Cortisol dysregulation shifts metabolism toward fat storage.
Poor sleep: Sleep deprivation reduces metabolic rate and increases metabolic efficiency (the opposite of what you want when trying to lose weight).
Nutrient deficiencies: Iron, iodine, selenium, zinc, and B vitamins are all required for optimal thyroid function and metabolic processes.
Our Assessment
I evaluate complete thyroid panel, resting metabolic markers, body composition assessment, hormonal status, nutrient levels (iron, iodine, selenium, zinc, B vitamins), fasting insulin and glucose, and cortisol pattern. This identifies specific, treatable causes of metabolic slowdown.
What We Do: Revving Up Your Engine
Thyroid optimisation: Ensuring your thyroid is functioning at its best, not just within the reference range.
Build muscle mass: Progressive resistance training is the single most effective way to increase metabolic rate long-term. Every kilogram of muscle burns approximately 13 calories per day at rest.
Increase protein intake: Protein has the highest thermic effect and supports muscle maintenance. I recommend 1.6-2.2 g per kilogram of body weight for those looking to improve body composition.
Avoid metabolic adaptation: Strategic approaches to calorie intake that prevent the metabolic slowdown associated with chronic dieting – including diet breaks and reverse dieting.
Increase NEAT: Simple strategies to increase daily movement – standing desks, walking meetings, taking stairs – can add 200-500 calories of daily expenditure.
Optimise sleep and hormones: Quality sleep supports metabolic hormone production, and addressing hormonal deficiencies directly improves metabolic rate.
Conclusion
A “slow metabolism” is usually not a fixed trait – it is a modifiable state with identifiable causes. By optimising thyroid function, building muscle, adjusting nutrition, and addressing hormonal factors, most people can meaningfully increase their metabolic rate. If you feel your metabolism is working against you, book an assessment at our practice in Zürich Seefeld.
