The scale is fickle: We lose weight when we pee or when we do a sweaty workout. We gain weight when we eat or drink or put on a sweater. But how much does that kind of fluctuation really impact the numbers we see? I weighed myself 15 times in one day to find out.

Is today the day you're going to start working out more often? Or are you just getting back to what you used to do before all the holiday parties messed with your schedule? Either way, it's time to get started. We've picked out six workouts that are perfect for your first (or second) day back.

Weighing ingredients gives you the most accurate, reproducible (and tasty) results (especially in baking), but not all recipes list their measurements by mass. Luckily, King Arthur Flour has put together a handy weight chart for a wide variety of ingredients.

Even if your teen needs to lose weight, talking to them constantly about their weight isn't the best strategy to help them to be healthy, according to the American Academy of Pediatrics (AAP). Focusing on weight or appearance can push kids toward eating disorders. Instead, it's better to forget about the scale and just help your kid to develop healthy habits.

Smart scales that track your weight over time aren't exactly pricey, but they're kind of boring. If you have a dusty old Wii Balance Board and a Raspberry Pi sitting around, Initial State shows you how to build one that will dish out some snark with your weight tracking.

Your BMI, or Body Mass Index, gives you a number designed to indicate whether you are at a healthy weight or not. But as we've pointed out before, it isn't always a reliable measure.

There's a huge amount of attention given to the health issues associated with obesity. However, we're big believers in the saying "coincidence is not causality". Visit any fitness-related website and you'll see that it's not enough to be thin – you also need to be fit. Nonetheless, the fact remains that body weight and composition remain significant indicators for health issues such as heart disease and diabetes. So, how do we know what our optimal body weight should be?

Obesity levels are on the rise, but is it all in your head? If it is, you'd better stop trusting your head: new research suggests that under-estimating how much you actually weigh is on the increase (a bit like waist sizes).

It sucks being discriminated against, whether that's on the basis of your race, gender or the fact that you don't fit in a regular airline seat. However, stopping discrimination against (and abuse of) fat people could be near-impossible.