While you can't completely transform your body in just one week, it's possible to add a small amount of fat to your frame in that time. If you wish to gain more weight, extend your efforts over the next weeks and months until you reach your desired size.

Your girlfriends may be envious, but struggling to put on weight may be as difficult for you as it is for them to lose it. If you want to gain weight healthfully, you need to follow the same healthy diet principles as those trying to lose.

Weight control is all about calories in vs. calories out. To gain weight, you'll need to take in more calories than you burn, and gaining 2 pounds per week requires eating 1,000 extra calories each day. Exactly how many calories you'll need overall, however, depends on your body size, activity level, age and gender.

It seems like gaining weight should be a breeze -- and it is, if you don’t worry about nutrition -- but increasing calories and eating healthy foods means you can’t rely on sugar-rich foods. Beans can support your efforts in this.

The average adult should obtain between 10 and 35 percent of her daily calories from protein, says registered dietitian Cara Rosenbloom.

Macronutrients -- the big three of protein, carbohydrates and fat -- are the cornerstone of any dietary plan. The U.S. Department of Agriculture notes that all three are important to your health, but balance is important. The best ratio for you depends on age.

If you want to eat a healthy diet, you'll need to understand the five food groups. The five food groups are vegetables, fruits, grains, dairy and protein. A healthy, balanced diet will include food from each group.

When consuming a diet based on a certain calorie amount, like following a 2,800-calorie diet plan, make sure to balance it properly. The healthiest diets feature fruits and vegetables, whole grains, lean meats and lowfat or fat-free milk products.

Diet and exercise both play an important role in helping women successfully tone up, which requires losing excess body fat and building or maintaining lean muscle mass. Daily calorie control, choosing foods that help you stay lean and regular exercise maximizes toning results for women.

If you eat too little, make poor food choices or don't eat often enough, you may feel a lag in energy on your weight-loss diet. To keep energy levels up on a low-calorie diet, you need to eat nutrient-rich meals throughout the day. Consult your doctor before starting a weight-loss diet.

To function properly, the human body needs to maintain homeostasis, or equilibrium. It does this, in part, by maintaining pH, a measure of alkalinity and acidity in the body, also called acid-base balance. Your diet plays a major role in maintaining the acid-base balance.

Losing weight successfully has a lot to do with the foods you choose to include in your diet, not just the number of calories you've eaten at the end of the day.