Sunday, January 25, 2009

Why Do I Weigh More at Night?

Martica Heaner, MSN Fitness and Weight Loss Expert

Q: I weigh myself both in the morning and again at night. In the morning I'm around 193 pounds, but in the evening, my weight sometimes hikes up to 204 pounds. I use the same scale and weigh in the nude, so I feel like my readings are accurate. My friend says that I have a water-retention problem. What can I do to treat this?

A: It's normal for body weight to fluctuate widely throughout the day. It's likely that your weight in the morning, and especially after you've used the bathroom, is at its lowest since you have probably not consumed any food or water for the past 12 or so hours.

How much and what kind of food and fluids you've consumed, as well as how much and how often you've evacuated, and even how much you have sweated all play a role in the pounds that register on the scale at any given point during the day.

Be careful not to mistake the increased scale weight as a conclusive sign that you are gaining or losing weight because going by pounds alone can often be misleading. While most people cite one number as their current body weight, it may be more realistic to cite a range, since the number does fluctuate daily. Most weight-loss programs advise to weigh at the same time of the day to try to minimize this variation. But still, if you were to weigh yourself every two or three hours you are likely get a whole range of weights, and here's why:

You can even sit in a sauna and sweat off five pounds, but that doesn't mean that you've lost five pounds of body fat. In fact, you'll gain that 'weight' right back after you replenish the fluids you sweated out. Water is retained and lost throughout the day and while it may be contributing to your varying readings, these fluctuations are most likely normal, and not necessarily the problem that your friend suggests. (If you have signs of bloating, check with your physician, however.)

If you eat a meal that consists of lots of plant foods like beans, grains, veggies and fruit, the food might weigh quite a lot because of all the fiber and water in it. On the other hand, you could eat the exact same amount of calories in the form of processed high-carb or high-fat foods and since this food is very condensed (much of the fiber and water is processed out of it), it's very light. If you ate the more healthful food you might take in a couple of pounds of actual food that would actually make you seem heavier if you weighed yourself after eating it. The processed item such as a fluffy, light croissant may not register as much extra scale weight at all even though it's very high in calories.

So does the heavier-weighing food make you fatter? Not at all. Here's why: The body gains weight from accumulating more stored body fat by eating more calories than are expended over time. (You can also gain more weight for other reasons such as increased muscle, but you would need to be doing progressive, heavy resistance training and eating more calories over time.)

When you eat a large meal, and if it's an unprocessed, plant-based meal, it's likely to be lower in calories, even if it has greater volume. Check out this comparison from the book Picture Perfect Weight Loss (Grand Central Publishing, 2003) by chiropractor Howard Shapiro. One small muffin is around 720 calories, and a huge platter consisting of an entire pineapple (that weighs several pounds), half a melon, half a papaya, plus two pears, some grapes, kiwi and two small whole-wheat rolls are also 720 calories. Not only would it would be nearly impossible to eat the healthful meal at once (who can eat an entire pineapple without feeling stuffed?), if you managed to even eat half of this, you would have ingested a pound or two of food, compared to a few ounces by eating the muffin.

So after eating this plant-based meal, you would temporarily weigh more while the food is going through your digestive system. That doesn't mean you are heavier, though, because it's the caloric load that ultimately leads to excess body fat. In reality you might only be able to eat about 400 or 500 calories worth of this healthful meal, even though you ate much more in terms of volume of food. Most of the fiber and water in the plant-based meal is calorie-free and would be excreted out, NOT turned into extra body fat.

Another example in the book compares two 400-calorie options: a high-fat choice such as three small ribs or one egg roll, or a large meal consisting of brown rice, vegetable soup, a fortune cookie and Chinese-style broccoli and shrimp.

Chances are that you'd not feel full eating only one egg roll or a few ribs. One could easily eat double, triple (or more!) than the 400-calorie serving shown to make a meal. So you could easily take in 800 to 1,600 calories at one sitting choosing the high-fat options. In comparison, it might be difficult to eat the entire healthful meal shown. But even if you did, it would consist of only 400 calories. So you'd feel satiated, but you still be dieting because you are controlling your caloric intake with these plant-based foods that are high in both fiber and water.

The major point to keep in mind is that, while scale weight is important, it is not a total reflection of your body composition such as the amount of body fat and/or muscle that you have. When losing large amounts of weight, the scale is a useful tool to gauge the change. But avoid getting too nit-picky with daily readings, and look for trends over time. If you have access, try getting your body composition measured, either through a DEXA scan at your doctor's office, or by using body fat calipers by an experienced trainer at your gym. An underwater weighing tank in the exercise physiology department at a local university is another option (some gyms occasionally offer measurements taken in portable tanks). It's also important if you are losing weight to make sure to include some resistance training in your routine so that you can minimize the amount of muscle loss that inevitably accompanies weight loss.

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