Body weight fluctuates based on energy in vs. energy out although there are some instances where genetics play a role.  In most cases we can control our weight status with our eating and exercise habits.   View the example below to see how increased food consumption can prevent one woman from reaching her goal. 

Example

Ms. Jones is a 32-year-old woman who is 5’5” tall and medium framed.  She currently weighs 145 pounds and is frustrated with her inability to lose another 10 pounds.   She exercises regularly and believes that she eats well.  Let’s take a look! Physical Activity: Ms. Jones walks briskly for 30 minutes each day followed by a 15-minute session with her hand weights.  She’s determined this routine burns off an average of 160 calories. Ms. Jones is an administrative assistant, which keeps her pretty stationary during her 9-hour workday.  It’s been determined that she expends approximately 800 calories at work.  Based on her height, gender and age, her natural energy expenditure (basal energy expenditure) amounts to 736 calories. In total, she is expending 1696 calories per day. Nutrition: Ms. Jones is confident that she eats a low-fat, high-fiber diet loaded with fruit and vegetables, but she never pays attention to her total calorie consumption.  Ms. Jones sought out a dietitian and wrote down her food intake for three days.  The dietitian analyzed her food diary and determined that Ms. Jones consumes an average of 1950 calories per day. Energy In (1950) - Energy Out (1696) = Excess of 254 Calories The excess 254 calories will become stored energy for Ms. Jones and will take the form of body fat.  Although she is exercising regularly, she is consuming too much energy for her body and daily routine.  Ms. Jones will not reach her goal until she cuts back on her food intake.

Does Nutrition Only Affect My Physical Appearance
No, nutrition not only affects our physical appearance it affects our health. An individual can maintain a very healthy weight yet suffer from high blood pressure, clogged arteries and high cholesterol due to the intake of poor-quality food.  Using the example above, if Ms. Jones chose to eat all 1696 calories (the amount needed for weight maintenance) from high-fat, high-sodium, processed food, she would maintain her weight, but her health would be compromised. She would be at greater risk for developing disease yet appear healthy. For More Information, please see Nutrition & Health.