These are tips to follow that I try to obey when I can to stay slim. Unfortunately, my job requires me to eat out a lot and in large portions (my industry is mostly male), and my husband really likes carbs for dinner.
Either way, these are very good tips to follow to get and stay skinny.
1. Keep your metabolism up: Get plenty of sleep, at least 8 hours a night.
2. Don't let your metabolism slow: Always eat breakfast. Try to never skip meals. And, treat yourself to indulgences every once in a while.
3. Avoid preservatives. Try to have freshly cooked items as much as possible. Freshly cooked items does not change to fat as efficiently as food with lots of preservatives. It's a common misconception to just count calories. Not all calories are created equal. Eating 500 calories worth of spinach is processed way differently by your body than 500 calories of cookies. It's a combination of quality AND quantity.
4. If you ate REALLY badly on a day, that night before you go to bed, boil a cup of water and squeeze the juice of a quarter wedge of lemon into it. Drink while still hot/warm. This lemon tea also does wonders to your skin if done for 3 days in a row. I don't advise doing it everyday. For an unfounded reason, I just don't feel comfortable doing this. Although, I know people who drink this every morning.
5. Eat 3 servings of veggies, 2 servings of fruit a day. Having citrus in your diet every day is beneficial if you are trying to lose weight. Grapefruit is especially effective.
6. Exercise. Even if it is 30 minutes once a week, it's good for your body. If you are trying to lose weight, it's best to do something aerobic and at a constant pace. For example, jogging at the same speed for 20 minutes. Also, for weight loss, it has been shown that running, ellipticals, and this sort of aerobic exercise is more effective than swimming.
Having more muscle/fat ratio produces a higher metabolism. Also, muscle has a greater capacity to keep the body hydrated. People with less fat stay hydrated easier.
7. Eat less at dinner than you do at any of your other meals. Only allow a small portion of carbs at dinner. No sweets for dinner either.
8. Eat till 80% full and STOP. Do not wait until you are very full to stop. 80% full feels like your stomach is comfortably satisfied (if this makes sense).
9. No eating 2.5 hours before bedtime. Sumo wrestlers actually eat a VERY large meal and immediately nap afterwards to build body weight. To be slim, there should be a good amount of time between food consumption and slumber.
10. Weigh yourself every morning. This will make you try harder to be healthy each day.
11. Drink lots of water. Forgo the juice and soda.
Most of the time, I'm not following these rules because my job/lifestyle do not permit it. But, if I see a pound creeping on, I refer back to these tips and keep my weight in check.