Weight (kg): tracking and trends

What is weight tracking

Body weight is one of the most commonly monitored health indicators. It reflects total body mass — the sum of muscle, fat, bone, water, and organs. Weight is measured with scales or smart scales that automatically send data to an app.

It is important to understand that daily weight and the true body composition trend are different things. During a day, weight can fluctuate 1–2 kg due to water, food, and intestinal content.

Recommended values

Weight norms are assessed using body mass index (BMI = weight kg / height m²):

• BMI < 18.5 — underweight
• BMI 18.5–24.9 — normal weight
• BMI 25.0–29.9 — overweight
• BMI 30 and above — obesity

However, BMI does not distinguish muscle from fat. Active individuals may have a high BMI with low fat mass. Therefore, it is important to evaluate weight together with body fat percentage and waist circumference.

Why weight may increase

Weight gain may be related to caloric surplus, decreased physical activity, hormonal changes (hypothyroidism, Cushing's syndrome, menopause), medication side effects (corticosteroids, some antidepressants), water retention (heart or kidney problems), or sleep deprivation. Sudden weight gain over a few days usually indicates fluid retention, not fat accumulation.

Why weight may decrease

Unintentional weight loss (>5% over 6–12 months) may indicate hyperthyroidism, uncontrolled diabetes, digestive disorders (celiac disease, inflammatory bowel disease), chronic infections, oncological diseases, or depression and appetite loss. Intentional weight loss through restrictive diets can also affect blood markers — especially iron, albumin, and electrolyte balance.

What to do next

If you notice an unexpected weight change:

• Compare with the previous trend, not with a single measurement
• Pay attention to accompanying symptoms (fatigue, swelling, appetite changes)
• Check thyroid markers (TSH, fT4), glucose, HbA1c
• If weight has dropped unintentionally >5%, consult a doctor

Tracking weight alongside blood tests helps see the bigger picture — for example, whether weight gain coincides with changes in the lipid panel or signs of insulin resistance.

Tracking over time

Measure at the same time (ideally — in the morning, fasting). Assess the weekly average, not the daily value. Normal daily fluctuations (1–2 kg) are physiological and related to hydration, salt, carbohydrates, and intestinal content. For women, weight may fluctuate with the menstrual cycle phase.

Questions for your doctor

1. Is my current weight within a healthy range for my age and build? 2. Which blood tests would help investigate an unexpected weight change? 3. Could my medications be contributing to weight changes? 4. What would be the safest weight loss or maintenance strategy in my case? 5. Should I track waist circumference or body fat percentage alongside weight?