Calculating your precise weight without a scale is an impractical and complex physics problem involving water displacement and density. You may apply such a formula to a cube or rod, which has a regular shape and fixed density. Your body, however, is much more complex. To calculate your weight using underwater weighing, you need a large pool, expensive equipment and help from a trained professional -- it's not usually something you can do at home.
A scale is the easiest way to figure your exact weight in pounds, but it doesn't reveal much more about the health of your body. You also don't need it to evaluate trends in your weight. A tape measure, the way your clothes fit, your body fat percentage, the mirror and your general feelings of stamina and wellness all offer information about the size of your body.
Consider Your Body Composition Instead of a Scale
If you've been faithfully exercising as part of a body transformation program, a traditional scale tells you how many pounds you've lost, but it can't tell you how much of the loss was fat of whether or not you've gained muscle. Muscle tissue is denser than fat and makes your body look lean and toned, rather than soft and pudgy. A body that has a greater percentage of muscle may look and feel more in shape, but weigh more than someone who has a greater percentage of fat.
Tracking your body fat percentage, which can be measured by a fitness professional using skinfold calipers -- or via a detailed and expensive process of air displacement or a bone-density X-ray scan -- helps you know if your body composition is healthy. Try to track your body fat measurements every month or two. A safe and doable change is losing about 1 percent of your body fat per month.
Measure Your Middle to Calculate Your Health
The size of your belly doesn't tell you how much you weigh, but it does provide information about your health. A waist circumference that's larger than 40 inches on a man or 35 inches on a woman indicates an excessive amount of belly fat called visceral fat. This insidious form of fat forms around internal organs and releases inflammatory chemicals that increase your risk of health conditions, such as cardiovascular disease and type 2 diabetes.
Luckily, traditional weight-loss methods for reducing calorie intake, eating whole and unprocessed foods, and getting more exercise help reduce visceral fat -- sometimes without notably changing your actual weight on the scale. A tape measure can help you determine if you're losing this dangerous form of fat. When your middle shrinks, you know you're making progress. Your clothing can give you a similar indication of visceral fat loss. You know changes are happening when your tight jeans zip up more easily or elastic waistbands feel less constricting.
To measure your belly, simply loop a tape measure around your middle just above your hip bone. Hold it taut, but not snugly, pressed into your skin. Relax your abdomen, too -- don't hold in your stomach.
Use the Mirror as a Measure of Your Weight
Having a target weight can be motivating, but ultimately, you want to look good and feel healthier. So, instead of looking at a number on the scale as a measure of change -- simply observe your body. If you look in the mirror and feel good about the image that stares back at you, then own it.
Photographs can be even better indicators of weight change because they record progress. When you see yourself every day, you may not notice small changes that add up to a transformation. Progress pictures can reveal how you change from month to month. Choose the same backdrop and pose in a bathing suit or other minimal clothing when taking these shots. Catalog them in a folder on your phone or print them out for comparison.
Check in With How You Feel to Measure Your Weight
Positive changes to your health aren't always reflected by the scale. A regular exercise routine, for example, may not cause you to measurably drop weight, but could cause dramatic improvements in your cardiovascular health.
Notice if your stamina to do daily chores changes; if it's harder or easier to carry the laundry up the stairs, walk the dog or clean up after the kids. As you become healthier and lose weight, these tasks usually become more doable, but if you haven't been taking care of yourself like you should and put on weight, they become more daunting.
The scale can sometimes lead to obsession, too. If you find yourself weighing yourself daily -- or multiple times per day -- and your mood being affected by the results, you could suffer from an unhealthy scale addiction. Your weight naturally fluctuates daily due to water retention, hormones and digestion. Evaluate your diet, sleep, exercise and hydration habits instead. If these are on point, you're living a life of balance and fostering good health.
- Psychology Today: Do You Suffer from Scale Addiction?
- Plos Blogs: Why the Body Mass Index (BMI) Is a Poor Measure of Your Health
- Wake Forest Baptist Health: Belly Fat Measurement and Weight Management: Waist Circumference
- American Council on Exercise: What Are the Guidelines for Percentage of Body Fat Lost?