The National Heart, Lung, and Blood Institute indicates that a healthy weight for a woman who is 5 feet, 4 inches tall ranges from 110 to 140 pounds with a BMI of 19 to 24. A woman whose BMI score is above 25 falls in the overweight category and 30 and above falls in the obesity category.
The Bottom Line. Both obesity and being out of shape increases your chances for a number of diseases and early death. However, the person who is lean but doesn't exercise regularly may not be in such good health after all. Being active and fit is good for you regardless of your body size.
“Obesity incidence starts increasing in one's twenties and peaks at 40 to 59, and then decreases slightly after age 60,” says Craig Primack, MD, an obesity medicine physician at the Scottsdale Weight Loss Center in Arizona.
As you age, your muscle mass decreases and your fat mass increases. Fat is less metabolically active than muscle—you don't need as many calories to maintain fat as you do to maintain muscle. Hormonal changes can also lead to weight gain.
How quickly will you lose weight? The volunteers reduced their waist sizes by an average of 1 inch for every 4lb (1.81kg) they lost. So if you lose 1lb (0.45kg) a week you could hope to reduce your waistline by an inch after four weeks.
While being overweight is a precursor to obesity and, like obesity, can increase the risk of diabetes, heart attack and stroke, it's also possible to be overweight and still healthy, especially if you're free from chronic diseases like hypertension or diabetes.
Muscle is denser than fat, and as it is more compact within your body, as you gain muscle mass, you end up looking thinner, no matter your physical weight. So, if you've been doing a lot of strength training lately, it's likely this is the reason that you're looking fantastic but not dropping those numbers.
BMI ranges
below 18.5 – you're in the underweight range. between 18.5 and 24.9 – you're in the healthy weight range. between 25 and 29.9 – you're in the overweight range. 30 or over – you're in the obese range.
It's possible to gain muscle and reduce body fat without actually seeing a change in your weight. This happens when you lose body fat while gaining muscle. Your weight may stay the same, even as you lose inches, a sign that you're moving in the right direction.
You've gained muscle.
And here's an often overlooked fact: Muscle tissue is more dense than fat tissue. So as you gain more muscle and lose fat, you change your overall body composition, which can result in a higher weight, but a smaller figure and better health.
What exactly counts as being "skinny?" Some healthcare experts believe a BMI in the 15-18 range to be clinically underweight. This seems to fall pretty close to what many everyday people consider to be "skinny" with a BMI of 18 or lower frequently listed as the indicator of someone considered to be slim.
The BMI calculates height and weight to come up with a score that is indicative of a class of health risk. A score of 18.5 to 25 is typically considered a healthy BMI. A BMI of 25 to 29.9 is considered overweight, while a BMI of 30 or greater is considered obese. An overweight status begins to constitute a health risk.
BMI isn't perfect
BMI is not a perfect measure of weight or obesity. It often identifies fit, muscular people as being overweight or obese. That's because muscle is more dense than fat, and so weighs more.
How muscular you are: A few people have high BMIs but don't have much body fat. Their muscle tissue pushes up their weight. An example: "A football player or a body builder who is very muscular. Their BMI shows up pretty high, and yet their body fat is actually pretty low," Kahan says.
To do it, breath normally and wrap the tape around the part of your stomach that's roughly two inches above your hips. The resulting number is your waist circumference. In general if you're a woman, you want a measurement that's less than 34.5 inches. If you're a man, a number below 40 inches is ideal.
Multiple regression tells us that on average, for every 8.5 pounds lost, people dropped an inch off their waist. (And for every 1.5 kilograms lost, people dropped a centimeter off their waist.) Every 10 pounds lost was accompanied by 1.18 inches of waistline reduction.
Many women also notice an increase in belly fat as they get older — even if they aren't gaining weight. This is likely due to a decreasing level of estrogen, which appears to influence where fat is distributed in the body.
Changes in total body weight vary for men and women. Men often gain weight until about age 55, and then begin to lose weight later in life. This may be related to a drop in the male sex hormone testosterone. Women usually gain weight until age 65, and then begin to lose weight.
Over time, studies have shown that metabolic rate (how fast we burn calories) starts to slow down by 2 to 3 percent each decade, beginning in our 20s. It becomes more noticeable between ages 40 and 60.