"I tried that diet and lost 8 pounds in the first week!"

"I've gained three pounds in one day! It must have been the cookie I ate or maybe the mashed potatoes!"

These are comments I hear so often that I decided it would be a good topic for an article to help people have a better understanding of the fluctuating numbers on their scale. It is important to understand, when we step on a scale, it is measuring every part of our physical being at that moment in time, which means it measures our fat, muscles, organs, tissue and water weight.

Water weight can affect your total weight anywhere from 1-10 pounds and sometimes even more. It is important to understand what kinds of dietary factors can make these fluid shifts happen. To start, many of the high protein, low carbohydrate diets such as Atkins, or the beginning of South Beach can cause a dramatic shift in your water weight. This is because as you significantly cut back carbohydrate intake your body starts breaking down the stored carbohydrates (glycogen) to use as energy, and this breakdown causes the body to excrete large amounts of water. Once the body begins to use stored fat for energy, weight loss slows. This is why most people lose a significant amount of weight right away on a low carb, high protein diet. Extreme low carb, high protein diets can often lead the body to a state of dehydration because of the significant fluid loss.

What is misleading is when a person following a low carb plan eats a carbohydrate-rich food they can easily gain 1-3 pounds. However, this weight gain is just your body replenishing the fluid it lost and is not gained fat. I have had numerous clients struggle with this and they end up yo-yoing back in forth with fluid weight thinking that it must be the half cup of rice they had the night before that caused them to gain that 2 pounds when in fact eating the rice just allowed them to regain some of the fluid they had lost from following a strict low carb plan. The fact is carbohydrates do not affect your weight quite that simply. Excess refined carbohydrates can strongly stimulate insulin production, which promotes fat deposition and increases appetite. This kind of weight gain will happen gradually, not dramatically overnight.

Sodium is another dietary component that can lead to fluid gain. Sodium can cause the body to retain fluid, which can lead to these frustrating daily weight fluctuations. Some people are more sensitive to sodium than others. Watch your diet and see if your weight gain corresponds with a high sodium meal the day before. For example, eating out in restaurants can often increase your sodium intake significantly.

The best way to tell if you are retaining fluid is to pay attention to your body. If you get indentations on your ankles and lower legs from your socks then you are retaining fluid. If you wear rings and they become tight and leave an imprint in your fingers when you take them off then you also likely retaining fluid. Any kind of puffiness in your skin is a good indication of water weight.

The bottom line is that it takes 3500 calories to gain or lose 1 pound of body fat. This equates to an extra 500 calories a day over 7 days to gain a pound. This means if you gained 3 pounds in one day you can chalk it up to fluid weight otherwise you would have had to consume10,500 extra calories that day which is not likely! True weight gain happens gradually and likewise we lose it gradually. Check your weight weekly instead of daily and look for overall trends. If you are seeing dramatic daily changes in your weight, it is likely the ever-changing shifts of our bodies' water weight.

Meri Raffetto is a Registered Dietitian and owner of Real Living Nutrition Services. Sign up for her monthly newsletter to learn what's new in nutrition, weight loss success stories, healthy recipes, and more. Go to http://www.reallivingnutrition.com for more details.