I had a real hard time with this when I started maintenance, until I read in several sports nutrition books that one of the best ways to figure out if you're getting dehydrated is to weigh yourself before and after exercise. I tried it, and in the summer that could be several pounds lost for me in less than an hour, even drinking a lot. That really got me thinking about the impact of hydration levels on weight. I took it a step farther then and experimented with weighing myself before and after meals, using the bathroom, showering, different times of day. Over several days, I'd notice differences, sometimes big differences, due to menstrual cycle, quantity and quality of calories, exercise including muscle soreness and dehydration, etc. I came to the conclusion that hyrdation levels are the largest, by far, reason for short term weight changes and must be properly accounted for in using weight as a measure of body fat loss. I cannot do that with one weight measurement in a week.
These are my real weights (in lbs) over the last couple of days. They are measured on my home scale while not wearing any clothes, unless otherwise noted. My other stats: between 5'7" and 5'8" tall, BMI hovers around 27, body fat is 25-27% or so, and I'm a real comfortable size 12 getting into a 10 once in a while. I'm hovering at the top end of my maintenance range right now. For the record, I usually only weigh myself about twice a day, unless I'm trying to assess dehydration when I exercise in the heat (this is Tucson after all), when I also weigh myself before and after exercise. I did this log to illustrate the point. Gain/loss is only calculated where the scale and state of dress didn't change between weigh-ins.
Code:
Total measured gains: 13.5 lbs. Total measured losses: 13.3 lbs. Net gain for two days: 0.8 lbs. Time Weight G/L Note Thursday 9:25 pm 175.2 **** Before bed Friday 2:05 am 174.0 -1.2 Bathroom (BR) 4:20 am 173.4 -0.6 Up for the day 5:20 am 176.2 +2.8 After b'fast 5:25 am 174.8 -1.4 BR 5:50 am 174.0 -0.8 After shower & BR 6:00 am 177.2 **** Dressed, no shoes (D) 6:30 am 176.0 -1.2 Leaving for work, D 7:20 am 169 **** Work scale (W), D 8:50 am 170.5 +1.5 After snack & BR, W,D 11:20 a 168.5 -1.5 Before lunch, W,D 12:00 p 170.5 +2.0 After lunch, W,D 4:00 pm 176.4 **** Home, D Saturday 12:15 a 178.2 +1.8 Home, D, after dinner & show 12:20 a 175.4 **** Undressed, ready for bed (!) 5:00 am 173.6 -1.8 BR 6:45 am 172.6 -1.0 Up for day 8:00 am 174.0 +1.4 After b'fast 9:15 am 172.6 -1.4 After exercise 6:00 pm 176.6 +4.0 After dinner 8:30 pm 176.6 +0.0 Ready for bed Sunday 5:15 am 174.2 -2.4 Up for day
Daily circumstances: Friday was a long day, dogs woke me up extra early, went to work and then to dinner and a show with my parents and DH. Got home very late and pretty much fell into bed. Saturday, got up, worked out, went shopping, then came home and relaxed and went to bed little early. My calories both days were about 2200 calories, close to my maintenance level, and I had reasonably healthy food--no big sugar binges. More veggies on Friday than Saturday. So, should be very minimal change to my body fat levels. Neither were particularly exceptional days, either good or bad.
Over just slightly more than 48 hrs, I logged over 13 lbs of both gains and losses. Noticing there were long periods of time when I couldn't get to the scale, or couldn't assess a change due to other variables, scale, clothing, etc, the real changes certainly added up to much more than that. These are real WEIGHT changes due to normal fluid variations over a couple days. They are NOT body fat changes. That is a big number--13 lbs. Even the morning numbers I formally track (173.4, 172.6, & 174.2) changed by more than a pound.
Over time, I found other factors affect my weight pretty consistently (you guys will have to take my word for these).
If any of these events happen, I make a mental adjustment to my weight, and then watch to see if it returns to normal. There may be other factors I haven't discovered yet.
So what was the lesson for me? How do I use weight as a tool to track where I am? For me personally, I look for PATTERNS. For example:
My assessment of the two days above based on my normal patterns: I'm still on the high end of my weight range from the marathon, but I'm happy that I'm back in it now. I need to make sure that drops another pound or two in the next couple days. If it doesn't, I need to look at the possibility that some of the 'carbo loading' from last week has gone to my butt--I wasn't eating so well last week and that could have lasting implications. I did reasonably well on the food plan these two days, even with a lot of eating out and such, but the scale wasn't budging. Fine for maintenance, but I'd still like to drop a few more pounds. I need to step that up a notch, carve out a couple hundred calories a day, and get the scale moving in the right direction again.
Now, the number on the scale is very emotional for most women and I'm not immune to its effect either. For many people, weighing once a week is a fine and sane method for tracking body fat loss. If that's working for you keep doing it. But the only thing that worked for me was understanding the my weight patterns, and that requires more data. If a small weight gain after a week or two of hard, on-plan work upsets you, I'm a strong advocate for understanding your weight patterns, and seeing how those play into the weekly number. I would also recommend that this is not a license to kid yourself about weight gain to be concerned about, more than a couple off plan days for example, but it is good to have the facts in to make an appropriate plan.