I have a very high metabolism. Some envy me, others find me too skinny. What troubles me though, is that I don&#x27;t have weight as a heuristic in regards to my health. I sometimes worry, as everything else is quite ambiguous. Energy levels depend on sunlight, sleep and so on. How often I fall sick is equally dependant too many variables for it to be a reliable indicator.<p>I would love for something like this to be reliable&#x2F;easy&#x2F;cheap so I have something I can turn to when I feel uneasy about my health.