Frequently Asked Questions
What is BMI and how is it calculated?
Body Mass Index (BMI) is a value derived from a person's weight and height. It is calculated by dividing your weight in kilograms by the square of your height in meters (BMI = kg/m²). It provides a simple numeric measure to assess whether a person has a healthy body weight for their height.
What is waist-to-height ratio (WtHR) and why is it important?
Waist-to-height ratio (WtHR) is calculated by dividing your waist circumference by your height. It's an important indicator of health risks associated with excess abdominal fat. Unlike BMI, WtHR takes into account where fat is distributed on your body, which is crucial because central (abdominal) obesity is a stronger predictor of cardiovascular diseases and other health issues.
How often should I measure my health metrics?
For most people, measuring once a week is sufficient to track progress without becoming obsessive. Choose a consistent day and time, such as Monday mornings before breakfast, to ensure your measurements are comparable. If you're making significant lifestyle changes, you might want to measure more frequently, but avoid daily measurements as natural weight fluctuations can be discouraging.
How do I measure my waistline correctly?
To measure your waistline correctly, stand up straight and breathe out. Place the measuring tape around your bare abdomen just above your hip bone, which is typically at the level of your navel. The tape should be snug but not compress the skin. Take the measurement at the end of a normal breath out.
What is visceral fat, and what does the visceral fat estimate tell me?
Visceral fat is the fat stored around your internal organs (rather than just under the skin), and it's more strongly linked to cardiometabolic risks like type 2 diabetes and heart disease than overall body fat is. You can't measure it directly without a CT or DXA scan, so Health Tracker estimates it using an anthropometric formula based on waistline, thigh circumference, age, and (for women) BMI. It's an optional, free estimate rather than a diagnosis — fill in thigh circumference on the dashboard (and date of birth in Options) and it'll appear alongside your other metrics. See the About page for the full formula and sources.
Why do you ask for my date of birth (age)?
Date of birth is optional and only needed if you want a visceral fat estimate. Age is one of the inputs — alongside waistline, thigh circumference, and (for women) BMI — in the anthropometric formula we use to estimate visceral fat, the type of fat linked most strongly to cardiometabolic risk. We store your date of birth rather than a fixed age so the estimate keeps working accurately as you get older, instead of going stale. See the About page for the full explanation and sources.
Why do you ask for thigh circumference?
It might seem like an odd thing to track, but thigh circumference plays a specific role: research has found that, unlike waist circumference, it's negatively associated with visceral fat once waist circumference is accounted for. Subtracting a thigh-based estimate from your waist measurement helps isolate visceral fat (the fat around your organs) from subcutaneous fat (fat under the skin) without needing a CT or DXA scan. It's completely optional — see the About page for the research behind it.
How do I measure my thigh circumference correctly?
Stand upright with your weight evenly distributed on both feet and legs slightly parted. Wrap the tape around your upper thigh about 1cm below the gluteal fold — the crease where your buttock meets the back of your thigh — holding it horizontal and snug against the skin, not pulled tight. This is typically also the widest point of the thigh.
Is my data secure and private?
We take data security and privacy very seriously. Your health data is encrypted and stored securely. We do not share your personal information with third parties. You can read our full Privacy Policy for more details.
Can I export my health data?
Yes — every measurement, tag, and generated health report you've logged can be downloaded as a single CSV file, which opens in spreadsheet programs like Excel or Google Sheets. Go to Options and look for "Export Your Data" under Data Management.
How do I delete my account or my measurements?
Both are available under Options in the Data Management section. "Delete All Measurements" clears your logged data but keeps your account and preferences; "Delete Account" permanently removes your account and everything associated with it. Both ask you to confirm first, and neither can be undone — consider exporting your data first if you might want it later.
What are healthy ranges for BMI and WtHR?
For BMI, the generally accepted healthy range is 18.5-24.9. For waist-to-height ratio, a healthy value is typically below 0.5 (or below 0.53 for men and below 0.49 for women). However, these are general guidelines and individual health factors should be considered. Always consult with healthcare professionals for personalized advice.