"One of the most frustrating moments for many dieters is the weekly weigh-in. Sometimes, the results on your scales seem to bear very little relation to the week you've just had. Maybe you've been really good - but not lost anything. Or you've had a couple of meals out, and eaten more than a few candy bars - and yet you've dropped a pound.
What's going on?
If you weren't dieting and weighed yourself every day, you'd still find that your weight wasn't steady: it might fluctuate by as much as several pounds. These fluctuations in body weight are commonly due to:
The amount you've eaten
Water retention is caused by drinking too little water, or eating too much salt. If you don't drink enough water, your body will cling onto its water supplies; make sure you're drinking enough. And if you eat too much salt, your kidneys hold onto water instead of excreting it.
Women commonly retain water during the few days of the month just before their period. This "phantom" few pounds will drop off as quickly as it went on. Some medications can also cause water retention.
Glycogen - sugar - is carbohydrate stored in the liver and muscles; usually more than a pound in total, along with three or four pounds of water. This is your body's energy reserve, and gets used up during the day if you're not taking in enough carbohydrates to supply your energy needs.
When you eat, your body replaces the glycogen store and the water that goes with it - leading to a weight gain on the scales, even if you've only eaten a moderately-sized meal. This is absolutely normal and should not put you off eating carbohydrates!
The Amount You've Eaten
Don't think about the meal you've just eaten in terms of calories - think in terms of weight. You could stuff yourself with pounds of fruit or salad for under a few hundred calories - but these pounds will show up if you stand on the scales straight after a meal. (Just imagine weighing yourself with all that food in your hands.) Once your body's had a chance to digest it, that food will disappear. The same applies with water - which has 0 calories, but definitely weighs something!
So how can you figure out whether you're losing weight or not, if your body's so prone to fluctuations? Try:
Only weighing yourself once a week, not every day
Always weighing first thing in the morning, before eating/drinking
Looking at the pattern of weight loss over time, rather than worrying if you've stayed the same or gone up in one particular week
Judging your success by the fit of your clothes, your energy and the good habits you're forming - not just by the number on the scales."