Is Your Metabolism “Broken”? Why You Feel Cold and Tired

Plenty of people feel cold all the time, run out of steam quickly and immediately blame a “broken metabolism” - but the reality is far more complicated.

If you cannot lose weight despite dieting, feel tired constantly and even sit in the office shivering in a jumper, it is easy to conclude your metabolism has supposedly “fallen asleep”. The phrase sounds catchy and fits neatly into any social media reel - medically, it is almost never accurate. In most cases, fatigue and feeling cold come from very different processes in the body.

What “metabolism” really means - and why it does not simply switch off

In everyday conversation, metabolism is often treated like a switch: on or off. Clinically, however, it refers to all the biochemical processes that keep you alive in the first place. If metabolism truly “shut down”, you would not survive - it is not that simple.

Even so, your day-to-day energy balance does shift constantly. It is influenced by several factors:

• Body composition (how much muscle mass, how much fat)
• Age
• Movement habits
• Diet and sleep

The largest share comes from the basal metabolic rate. This is the energy your body needs at complete rest: breathing, heartbeat, temperature regulation and brain activity. Typically, this accounts for around 60 to 70 percent of daily energy expenditure.

On top of that, you have:

• Digestion: energy required to digest and process food.
• Movement: planned exercise, but also spontaneous everyday activity such as taking the stairs, gesturing and getting up.

It is those spontaneous movements in particular - known as NEAT (Non-Exercise Activity Thermogenesis) - that are often underestimated. They can be the difference between the colleague who seems to “burn like a furnace” and the one who feels they gain weight just by looking at cake.

“Metabolism doesn’t simply collapse - the body gradually adjusts its energy use to our behaviour and weight.”

Why diets can make your metabolism feel “sluggish”

The body is built for survival and reacts very sensitively to prolonged, strict calorie restriction. When energy intake drops sharply, the body shifts into a savings mode.

This plays out on several levels:

• Spontaneous movement drops without you noticing - you sit more and fidget less.
• The body starts breaking down muscle mass if there is too little protein and no strength stimulus.
• Hunger and satiety hormones shift towards “Eat, now!”.

In real life, it often looks like this: the kilos fall quickly at first. After a few weeks, the scales stop moving even though the diet remains just as strict. Many people then think: “My metabolism is broken.” In most cases, what is actually happening is:

• You weigh less, so you objectively need fewer calories.
• Your day-to-day life becomes more sluggish because you are tired and move less.
• Your real calorie intake is underestimated (small snacks, drinks, “little bites”).

This is not a fault - it is a protective response that makes evolutionary sense. The body tries to hold on to fat reserves because it interprets the situation as a potential famine.

Always cold and exhausted: when an illness really could be behind it

There are circumstances where sensitivity to cold and persistent tiredness can point to a medical issue. A classic example is an underactive thyroid (hypothyroidism).

Typical accompanying signs can include:

• ongoing fatigue and low drive
• pronounced sensitivity to cold, especially in hands and feet
• dry, rough skin
• brittle hair, hair loss
• slight weight gain or a stubborn increase of a few kilos

“Thyroid problems can slow metabolism a little, but they are rarely the real reason for severe obesity.”

With an underactive thyroid, any weight gain is often more related to water retention than to pure fat gain. From the outside it can look like “sudden pounds”, but medically it is usually not dozens of kilograms.

Age has a much stronger influence on energy use. Over time, we gradually lose muscle mass if we do nothing to counter it. This process is known as sarcopenia. Muscle tissue is the most important “engine” for calorie use at rest. Less muscle automatically means a lower basal metabolic rate - even if the scales show the same number.

Hormonal braking caused by crash diets

If you spend years cycling through extreme diets, you may eventually notice just how hard weight loss becomes. Behind this is a hormone interplay that responds to weight reduction.

When body fat drops significantly, the following happens among other things:

• Leptin levels fall. This hormone normally signals: “I’m full”.
• Ghrelin levels rise. It increases hunger and intensifies appetite.

This is not a pathological disorder; it is part of the protective system. For those affected, though, it can feel brutal: more hunger, less satiety, and at the same time less energy and less urge to move. On top of that, many people lose muscle through low-protein diets, which pushes total energy expenditure even further down.

How to optimise your energy expenditure in everyday life

There is no miracle fix that “turbo-charges” your metabolism. But there are realistic, evidence-based strategies that help keep it stable - or nudge it up slightly.

Muscle mass as a natural calorie burner

The most effective lever is maintaining or building muscle mass. That does not necessarily require a glossy gym membership; what matters is regular resistance for your muscles:

• Strength training with weights
• Bodyweight training (press-ups, squats, planks)
• Strengthening exercises with bands or machines

“Every extra kilo of muscle burns more energy even at rest than the same kilo of fat tissue.”

Protein: not just for “gym bros”

Protein is the building block for muscles and tissue. If you eat too little protein, you increase the risk that, in a calorie deficit, your body will break down muscle tissue more aggressively. That lowers energy use - the opposite of what is helpful when you are trying to lose weight.

Protein also has a higher “digestive workload”. The body uses noticeably more energy metabolising protein than it does for fat or carbohydrates. Typical protein-rich foods include:

• Low-fat quark, yoghurt, skyr
• Eggs
• Pulses such as lentils, beans and chickpeas
• Fish and lean meat
• Tofu and other soya products

Sleep, stress and everyday movement: the overlooked levers

Consistently poor sleep puts your energy balance under real strain. Too little sleep:

• reduces insulin sensitivity
• increases cravings for sugary and fatty foods
• lowers motivation to move

Many people report that after bad nights they reach for snacks more readily and order fast food more often instead of cooking fresh meals. At the same time, the NEAT share drops because tiredness makes you move less.

Chronic stress also plays a role. Elevated cortisol affects appetite and fat storage, particularly around the abdomen. If you sleep poorly during stressful periods, sit a lot and snack on top, you create a perfect recipe for weight gain - without metabolism changing “magically”.

When it makes sense to see a doctor - and what you can do yourself

If you feel extremely tired for months, are very sensitive to cold, and notice changes in your skin and hair, it is worth getting it checked medically. A simple blood test can show whether the thyroid, blood sugar, full blood count and vitamin levels look normal.

At the same time, it helps to take an honest look at your routine. Useful questions include:

• How many hours per week do I actually move?
• How often do I eat protein-rich meals?
• How often do I sit for more than two hours at a time?
• How many hours do I really sleep per night?

Many people discover their metabolism is not “broken” at all. It is simply responding to too little movement, repeated crash dieting, lack of sleep and gradual muscle loss with age.

If you tackle those areas - with some strength training, more mindful protein intake, better sleep and more everyday activity - you often notice two benefits at once: more energy day to day and less of that constant feeling of being cold. These are usually the clearest signs that your energy balance is moving back into a better equilibrium.