Weight loss and your blood

When losing weight does not work, energy balance remains the basis: in the long run, weight changes through what you eat and what you burn. A blood test does not change that, but it can reveal factors that play a part in the background. A blood sugar balance that is drifting, a slow thyroid or prolonged stress can make it harder to lose weight.

An abnormal value can fit your situation, but rarely explains it completely. And a normal result is an answer too: you then know these measurable factors have become unlikely, and you can focus on food, exercise, sleep and habits you can sustain.

HbA1c reflects your average blood sugar over the past months. That makes it a more stable picture than a single glucose measurement, which depends heavily on the time of day and your last meal.

With excess weight, the body can become less sensitive to insulin, the hormone that regulates blood sugar. That can fit a gradually rising blood sugar and a higher risk of type 2 diabetes. Conversely, weight loss can improve insulin sensitivity. Insight into your blood sugar is not dietary advice, but it does show whether this area deserves attention in your case. It also gives a starting point to see change later on.

The thyroid drives the metabolism. If it runs slow, that can fit weight gain, fatigue, feeling cold and slower digestion. TSH is the first measurement to assess thyroid function; where needed, a doctor also looks at free T4.

Important to know: a slow thyroid is rarely the only explanation for excess weight, and the weight gain it causes is usually limited. Measuring is still useful here. Symptoms that can fit a slow thyroid also occur with many other causes. A result helps to confirm this lead or close it off.

Cortisol is a stress hormone with its own daily rhythm. An elevated value can be associated with prolonged tension, but a single measurement remains a snapshot; the time of sampling is weighed in the assessment.

The influence of stress on weight often runs through behaviour. Those who are under prolonged tension or structurally sleep too little tend to crave calorie-dense food, move less and find good intentions harder to sustain. Even without an abnormal cortisol value, sleep and relaxation are therefore a serious part of any weight loss plan.