Why Science Says You Can't Lose Those Last 5 Pounds

Never mind the "Freshman 15." It's the "Fifty 5" that is the real killer. Once you hit midlife, losing those final five pounds just becomes near-impossible for many people. It turns out, it may not be your dieting commitment as much as other factors -- including some environmental ones. Here are five reasons why science says you may be struggling:

You don't sleep well.
Sleep, it turns out, is the easiest way to lose weight. We've all been there: After a restless night of tossing and turning, we wake up exhausted and crave fuel for our bodies. As we start to nod off all day long, what do we do? Grab for food to give us a jolt. Ah, if only we had slept well.

WebMD says there are dozens of studies that say people who sleep less tend to weigh more. In one study that lasted 16 years, almost 70,000 women were followed. The results: Those who slept five hours or less a night were nearly a third more likely to gain 30 pounds or more than women who slept seven hours per night.

Sleep deprivation actually changes your basal metabolic rate, which means it slows down how many calories you burn from doing those basic life-sustaining activities, like breathing and maintaining body temperature. Combine that with your body's craving for additional "fuel" on the day after a bad night's sleep and there you have it.

Solution to those final five may lie in your bed. Get a good night's sleep!

You are exercising too much instead of eating less.
Sure we all know that weight loss is a combination of dieting and exercise. But science says it's more the dieting part. Decreasing food intake is much more efficient than increasing physical activity to lose weight. Think of it like this: You can not eat one bag of chips for 300 calories or you can run for half an hour.

To be fair, you really do have to do both. But for the final five, maybe try a little less intake? And just a caution: Science also has shown that exercising a lot can actually stimulate your appetite.

You don't wash your fruits and vegetables.
Pesticides on your fresh produce contain substances that increasingly have been linked to obesity and weight gain. The effects that environmental toxins have on weight actually begin very early in life. Recent studies have linked exposure to environmental pollutants while in the womb with being overweight and having excessive body mass index later in life.

As you age, your metabolism slows and it's harder to lose weight. Scientists have long noted that just the act of losing weight also slows our metabolisms. This excessive slowdown is called "adaptive thermogenesis," and researchers say it seems to occur because of increased concentrations of pollutants in the blood.

Jumpstart your diet by washing all produce thoroughly and trying to buy organic when you can. And some swear by detoxes as a component of successful dieting.

You keep leftovers in plastic.
BPA -- bisphenol A -- is an industrial chemical that has been around since the 1960s. It's in your water bottle, your storage containers, what you wrap leftovers in to keep them fresh. It also may be an enemy of the final 5 as it impacts your metabolism.

According to the Mayo Clinic, there is research showing that BPA can seep into food or beverages from those containers made with BPA. While the U.S. Food and Drug Administration (FDA) says BPA is safe at the low levels that occur in foods, others are more skeptical. The fight over the safety of plastics isn't new. As Mother Jones noted in this investigative piece published a few months ago, way back in 1987 they were discussing how BPA impacts the endocrine system -- the network of glands that controls metabolism.

Simplest solution: Ditch the plastic in favor of glass or products marked "no BPA." AARP, which recently ran a post on the topic, adds this tip: Wash your hands frequently when you're at work; toxic compounds known as PBDEs are often found in office furniture and carpeting.

Your thermostat is set too high.
While it's hard to fathom this being the case of a menopausal woman experiencing hot flashes, your room temperature may be too high. Lowering the thermostat helps your body produce a hormone that stimulates the growth of something called brown fat. Don't worry; brown fat is your friend. It keeps your organs warm by burning calories, which is a good thing. Brown fat tends to disappear with age, which is not such a good thing.

According to AARP's story, "Lowering your thermostat from 75 to 68 degrees stimulates brown fat and increases calorie burn by 100 calories a day." A little less optimism came from the New York Times when it reported on the brown fat study. The paper quoted Dr. André Carpentier, an endocrinologist at the University of Sherbrooke in Quebec and lead author of one of the new papers, as saying, "As for deliberately making yourself cold if you want to lose weight, there is still a lot of research to do before this strategy can be exploited clinically and safely.” Party pooper, that one.

- huffingtonpost.com