If you want to lose weight, your Apple Watch can help you sustain healthy habits, but it can’t actually monitor your progress. For that you need to step onto scales.

Any scale will measure your weight, but that is only part of the story. Whether you are dieting or bulking up, it is just as important to keep track of your body fat. The trouble is, this is notoriously hard to measure accurately. As I discovered when I bought a new Withings Smart Body Analyzer, if you think you already know your body fat percentage, you are probably way off.

After a brush with cancer prompted me to take my health more seriously, I began using run trackers to start my journey from dad bod to six pack.

At first, running was the only exercise I did. It helped me lose my love handles, but I ended up looking too skinny. I decided it was time to put on some muscle. While Apple Watch and other wearables are great for running, they’re not much help when it comes to bulking up. As I soon discovered, some of the best fitness gadgets don’t fit on your wrist.