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You’ve overhauled your diet, exercise most days and even though you’ve lost some weight those last few pounds just won’t seem to budge. So what gives?

Experts say despite your best efforts, there are some things that you may not even realize have a huge effect on weight loss. Here are 12 that may be messing with your slim-down plans:

1. You’re sleep-deprived.
According to a Gallup poll, 40 percent of people get less than 7 hours of sleep each night. Without that precious shut-eye time, the stress hormone cortisol— as well as blood sugar and insulin— all rise, which can make you feel hungry. Lack of sleep also causes insulin resistance, which makes it easier for your body to store fat, said JJ Virgin, a celebrity nutrition and fitness expert and author of the New York Times-bestselling, “The Virgin Diet.”

2. You use a hard workout as an excuse to eat.
Just because you torched 700 calories at the gym doesn’t mean it’s a free ride to eat whatever you want. You also can’t eat something with the intention of burning it off later, because too much exercise can lead to overtraining and weight plateau, said Yuri Elkaim, a nutritionist and fitness expert, and author of “The All-Day Energy Diet.” Instead, eat food that will fuel your workout and include a small snack for recovery.

3. Your thyroid is out of whack.
Thyroid function is important for metabolism and experts agree thyroid problems are one of the most undiagnosed problems that can get in the way of weight loss. What’s more, what many traditional medical doctors consider the norm for thyroid stimulating hormone (TSH) levels isn’t and they also don’t consider other symptoms when looking at thyroid function, Virgin said. Ideally, your TSH should be between .5 and 1 and an integrative or functional medical physician is your best bet.

4. You eat small, frequent meals.
You might think eating mini meals every 2 to 3 hours will help stabilize your blood sugar and prevent you from overeating, but it can actually drive your insulin up so you can’t access stored fat for fuel, Virgin said.  If you eat a combination of lean protein, low-carb fruits and vegetables, whole grains and healthy fats, you’ll feel fuller longer and still lose weight.

5. You’re eating too much sugar and you don’t even know it.
Blatant sugar isn’t the only problem, it’s the sneaky sugars in so-called healthy smoothies, yogurt, and processed foods that can wreak havoc on your waistline. Fructose is by far the worst because it goes straight to the liver where it makes fat. It also elevates your sweet tooth so you want more and bypasses satiety signals so you eat but you’re still hungry, Virgin said. So read labels and slowly cut down on sugar.

6. You’re stressed out.
A recent study found that women gain 11 pounds a year when they’re under stress.  Stress raises cortisol, which breaks down muscle and lowers serotonin, so you crave more sweet foods. What’s more, because cortisol lowers stomach acid, you don’t digest effectively so you’re left even hungrier.

7. You train too hard.
You’re a cardio queen but too much can actually backfire. Interval training is best for weight loss and you can also train less in a shorter amount of time. Be sure to keep cardio to 2 or 3 times a week, because it’s psychologically and physically demanding, Elkaim said.

8. You don’t eat enough fat.
Your body needs fat to burn fat but the key is choosing the right type of fat to eat. Healthy fats like those found in fish, avocado, grass fed butter, olive oil, coconut oil, and nuts and seeds are best.

9. You’re vitamin D-deficient.
Vitamin D is actually a pro-hormone that is responsible for many of the body’s functions and without it, you can’t burn off fat. So ask your doc to check your levels and eat vitamin D-rich foods like salmon, sardines and cow’s milk.

10. You eat too late.
You might have a bedtime snack habit, but it can prevent your body from burning fat at the ideal time at night so try to eat dinner at a reasonable hour and then close the kitchen.

“One of the key things you can do to lose weight is extend your fasting period when you go to sleep,” Virgin said.

11. Your body is toxic.
Environmental toxins are everywhere and they can actually disrupt your hormones, lower your body temperate and makes your body hold onto fat. You can’t completely eliminate toxins, but eating lots of fiber, protein, green vegetables, having good elimination, and reducing your exposure can help your body detox each day.

12. You yo-yo diet
You try to “be good” or hop on the latest diet craze, but this isn’t a good way to sustain weight loss and studies show it can even increase the chances for cardiovascular disease. Instead, put the focus on your health, not your weight and your self-image.

“It’s not so much what do I have to do to lose 40 pounds, it’s who do I have to become?” Elkaim said.