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Are you tracking your oral temperature and worried if it’s below 36.9 °C after meals or first thing in the morning? While it’s tempting to assume that such readings point to a sluggish metabolism or worse, the truth is far more nuanced. Let’s separate fact from speculation and explore what science really shows.

Yes, your body temperature often rises slightly after you eat a meal. This is due to a process called the “thermic effect” of food (sometimes called diet-induced thermogenesis). When you eat, your body uses energy to digest, absorb, and metabolize nutrients, and this energy expenditure produces heat.

The rise is usually small, often about 0.2 to 0.5 °C, depending on the size and type of meal. Protein-rich foods tend to create the largest thermic effect, while fats and carbohydrates produce a smaller one. The increase is most noticeable within the first hour or two after eating and then gradually returns to baseline.

So yes, it’s normal for your body temperature to be a bit higher after meals, and this is generally a healthy sign that your metabolism is working.

Forget the traditional rule of 37 °C. Modern studies have revised the average down to about 36.4 °C, and normal body temperature naturally fluctuates through the day. It tends to dip to its lowest point in the early morning and peak by late afternoon. A range of roughly 36.5 °C to 37.5 °C is considered healthy, so a reading of 36.4 °C in the morning and around 36.9 °C after meals is not unusual and generally falls within normal patterns.

A slower metabolism can influence body temperature, since metabolic processes generate heat. Research on long-term calorie restriction has shown a slight drop in core temperature—about 0.2 °C—likely as an adaptive energy-saving mechanism rather than a malfunction. Similarly, hypothyroidism can make people feel colder and affect energy levels, though body temperature usually remains within the accepted normal range.

Where the conversation becomes problematic is when low body temperature is linked to a long list of health issues without evidence. Some alternative health claims insist that failing to reach 36.9 °C during the day signals everything from obesity and poor hormone levels to weak liver function, low libido, chronic illness, poor skin, and compromised stress response. These assertions go well beyond what science supports.

A notable example is Wilson’s Temperature Syndrome, which attributes a variety of vague symptoms to low body temperature despite normal thyroid tests. This so-called condition is widely rejected by medical experts and has been criticized as both unscientific and potentially dangerous.

Instead of focusing on hitting an exact temperature, it is more useful to pay attention to broader signs that may suggest slowed metabolism or thyroid dysfunction. These include persistent fatigue, feeling unusually cold, dry skin, difficulty losing weight despite lifestyle efforts, mood changes, cravings, or digestive problems such as constipation and bloating. While not specific to temperature alone, these symptoms can indicate when something deserves further medical evaluation.

If you are concerned, the best next step is professional testing. A doctor can measure thyroid function and other metabolic markers to give a clear picture of what’s happening. In the meantime, supporting your metabolism with consistent healthy habits—nutritious meals, regular movement, quality sleep, and stress management—remains the most reliable foundation.

Yes, your metabolism does affect your body temperature, but modest deviations below the outdated 36.9 °C benchmark are usually not a sign of serious dysfunction. Evidence shows that healthy individuals often run cooler than 37 °C without ill effects. Rather than chasing specific numbers, focus on how you feel, your energy levels, and your overall health. And if your symptoms persist or worsen, consult a healthcare professional for guidance.

The key takeaway is that body temperature alone is not a diagnostic tool for metabolic health. It’s one piece of a much larger puzzle. Paying attention to patterns, symptoms, and lifestyle choices will give you a far clearer picture than relying on a thermometer reading.