Why Am I Gaining Weight Even Though I Do Not Eat Bad Foods or Snack a Lot?

You've done everything right. You pass up the pizza and avoid mindless snacking in front of the TV, so it can feel frustrating when lifestyle changes aren't preventing weight loss. Don't worry, a few simple changes can help get you back on the right track. If you're accidentally eating more than you need -- even from healthy foods -- you might struggle with your weight, even though you're eating healthy foods. Keeping a food journal and committing to engage in more physical activity may help you stop weight gain to help you get back to your goal weight.

Fluctuations in the scale, even by as much as 5 pounds, are completely normal. Retaining fluid from eating a particularly salty meal, from hormonal influences or from a tough strength workout, can make you seem heavier the next day. If those pounds stick around for a week or more, it's time to take notice.

The most common cause of weight gain is regularly eating more calories than you burn in a day. You may be committed to choosing only unprocessed, healthy foods, but large servings and high-calorie versions can still cause the pounds to pile on.

For example, if you're enjoying just one snack a day -- but that snack is a cup of healthy, raw nuts -- you're adding more than 850 calories to your meal plan. For a woman who needs only 1,600 to 2,400 calories to maintain her weight, that's one-half to one-third of your daily needs.

You can still include high-calorie, healthy foods as part of your diet, but stick to moderate portion sizes to avoid gaining weight. For example, choose one-quarter of an avocado, one ounce of seeds or one tablespoon of nut butter.

It's easy to forget all the bites of food and added calories you consume during the day, but those odds and ends can trigger weight gain. On average, people underestimate their calorie intake by an average of 30 percent, reported New York University professor and author Marion Nestle in a 2012 issue of The Atlantic. Make sure you count that fancy coffee drink, a homemade cookie in the break room at work, a cascade of samples at the warehouse store and the scraps off your child's dinner plate as part of your daily calorie intake. Keep a meticulous food diary to track your diet -- it might reveal that you're eating more than you think.

Make sure you measure your portion sizes, since it's easy to underestimate portion sizes. A serving of meat or chicken is about the size of your palm; a 1/2 cup of grains is only a small fistful and a cup of vegetables is a generous handful.

Dressings, sauces and other condiments can also pile on the calories. For example, you make a healthy choice with salad instead of a burger and fries for lunch. But add two tablespoons of ranch dressing, cheese, raisins, bacon bits, sunflower seeds and croutons and your healthy, light meal now exceeds 600 calories per serving. Stick to just one or two high-calorie additions at meals and, if you find yourself still hungry, eat extra servings of watery, fibrous vegetables or fruit.

While physical activity helps you maintain your weight -- you need at least 150 minutes of moderate-intensity cardio daily -- some workouts work better to control your weight than others.

If you've been doing the same cardio workout forever, consider switching it up -- after a while, your body adjusts to your workout of choice, and you'll see your results plateau. Add interval training, in which you alternate brief bouts of high-intensity work with bouts of lower intensity work, to two or three of your cardio workouts per week. You might try a different type of exercise -- one that your body has not yet become accustomed to. For example, use the elliptical instead of the indoor cycle or jog instead of swimming.

Make sure you're doing a variety of workouts; don't do cardio only. Strength training helps slow down the natural loss of muscle mass. If you don't preserve muscle, your metabolism naturally slows down and you gain weight with fewer calories.

Stress from bills, work or family concerns causes your body to pump out more of the hormone cortisol, which encourages fat gain. Your body can't distinguish between these modern-day stressors and the paleolithic stressors -- like a food shortage or being chased by a tiger. As a result, your body responds to chronic stress by holding onto extra fat, which it can use as a source of energy in the future. Stress hormones slow your metabolism to preserve energy, which could also trigger weight gain. Stress may also interfere with your sleep habits. Having not enough quality sleep affects the hormones that regulate hunger and satisfaction, so you may unintentionally eat larger portions and crave richer foods. Experiment to find techniques to deal with stress, such as yoga and meditation, to help regulate your stress hormone levels, and aim for seven to nine hours of sleep a night to avoid weight gain.

If you're certain your diet and exercise is on point, speak with your doctor about any medical reasons why you might be putting on pounds. Having an underactive thyroid or polycystic ovarian syndrome can cause weight gain. If you're on any prescription medications, these may be a cause of weight gain; discuss alternatives with your doctor.