Exercise considered harmful for weight loss (kidding, but read on...)

This is an effect I've witnessed before, but I still find it curious.

I weighed 164 last Friday morning. Rode my mountain bike 85 miles and climbed 14,000 feet at elevation (all above 9,500 feet) on Friday, Saturday and Sunday. Ate reasonably most of the weekend, with a big meal Sunday night to celebrate with friends. Still definitely burned more calories than I consumed for the three days.

My weight Monday morning? 166.

Since Monday I've been overwhelmed at work and have not exercised in the least. I typically commute by bike and mountain bike at least a couple times a week, but not this week.

My weight this morning (Friday)? 158.5.

That's down 7.5 pounds since Monday. I'm consuming about 1,500 calories per day, as I was last week. I believe that should equate to losing about 2-3 pounds per week.

So I think we can safely derive that exercise is bad for weight loss.

Ok, I'm kidding, but I've seen this pattern before and still find it surprising. Is it all / predominantly water weight? Does my body think it can "let go" of the water because I'm not exercising? Does it horde water (and other nutrients?) during times of intense exercise "just in case?"

Inquiring, exercise-oriented minds want to know.

Yeah, I want to know too. I'm maintiaining, eat the same cals every day. But when I go way on a trip, don't exercise, I lose weight.  Does this have to go with glucose in the muscles?

im interested to know this as well. i once didnt exercise for 1 week because i like to give myself breaks every now and then. i wasnt eating past dinner and i was down to 155 from 160. i started exercising the following week and my weight climbed back up to 160.

i think its a combination of eating more because we are burning more energy and building muscle which weighs more than fat. that was my rationale behind the loss/gain.

I would love to know the science behind this, too.

Big meal the night before the weigh in - Even though you might have burned the calories, you still have the residual in your large intestine adding to the weight as well as the water to allow it to pass through.

Do you drink coffee during the week? The diuretic effect of that plus a good BM can really change the numbers.

Because of such fluctuations it is reccomended that you weigh yourself only once a week at a time when your past activities and diet are the same week to week.  Also weigh yourself at the same time of day.  My time is Weds. morning after my BM and P

BUMP - I want an answer to this too. 

I'd have to agree with Marc.  Some of it may have been water weight and food from the larger meal.  If the meal (even healthy) had alot of sodium, you could be retaining some water there...and then in the next day or so, your body released it again.

Weight definetely does fluctuate a couple pounds up and down.  Usually it's just water and doesn't mean that you've gained any fat.

Hmm, good question. I know muscles use a lot of water when they are repairing themselves, that's a lot of water to lose though.

I have easily retained 8lbs of water that I could lose in 2 days of healthy eating.  I would drink on the weekend and weigh 158 on Monday morning and then by wed I would be at 150 or so.  It can be from dehydration, muscles retaining water for repair, and so on.   I can almost guarantee that its water weight..weird huh?

(disclaimer, I'm no scientist, a bike racer and triathlon wanna-be that reads alot and has lost +80 lbs since Aug. 2005...)

Part of your "fat burning" machine depends at the heart rate level you're training at. The ride you describe sounds like it took 8 or more hours. If your average heart rate during the course of the ride was between 65 and 75 percent of your max (generally 220 minus your age); that is the optimum fat-burning zone. Working out at this aerobic zone (with a heart rate monitor if you have one) can help you see where your fitness is improving, and where your heart rate needs to be in order to burn fat. The latest wisdom these days trains on the basis of time exercising compared to heart rate and the speed at which the body's engine "burns" most efficiently, and increasing the body's ability to adapt and recover through it's cardio fitness, combined with muscle and core strength, and flexibility. (there's a lot more technical information about an individual's VO2 Max heart rate, wattage output, and more, but you can look that up if you're interested.) Certainly there's an excercise physiologist somewhere on this site.

CC has lots of people complaining "I train all the time and don't lose anything." I would say it's because they are working out below the proper heart rate to burn fat. Lance Armstrong's trainer, Chris Carmichael, is a well-known expert on this type of training, also Edmund Burke out of Colorado if you want to google them or check some books out of the library.

Food is fuel -- you used all the fuel, ate a big meal, and then it took a while for your body to re-adapt. That fat burning is then lost through the operation of the body being alive; so you might not see the result until a few days later, as you described, especially if you went back to eating your normal daily calories with activity and all else held equal. Beyond that, your body turns "anaerobic" and uses the glucose available for energy, not fat. I wonder how many sports drinks you consumed during that ride; or GU or similar. Another poster mentioned the body's ability to "hold on" to sodium for 24-48 hours past the big workout. Sports drinks especially are guilty of making this happen, and diet sodas, too have alot of sodium. I have found that weigh-ins are +/- half a pound or more depending on water loss, I don't sweat it (LOL). I always try to weigh in via the same day, and same conditions, too much fluctuation can make you crazy.

It seems to take a few days for my significant exercise to catch up to me, too.  I'll get a workout of 1000-1500 calories and not eat more than about half of it and 2-3 days later the scale actually registers that plus my regular deficit.

No, it is not about sodium.  I am at 128 pounds... literally the lowest weight since I was about 13.  It does seem that I drop some weight when I am away from home, and otherwise inactive. I was away on a 16-day road trip. I didn't exercise, or even go for walks. Nothing physical whatsover. Lots of sitting and driving. I ate 100 calories less per day, which should not have  compensated for the lack of exercise.  Left weighing 127.50, came back weighing 126.75... my eyes about popped out of my head.  I had similar low weights in the days following, one day as low as 125.75... YIKES. After this for a couple weeks, I just ate more calories to get up to my target weight.

This has happened before... or at least didn't gain when I was away and didn't exercise. So I have wondered if there is something about exercise... not my imagination.  I was hoping someone else would know. Oh well, I'm having a busy day, but I remembered reading about this.

I'm always picking up used diet books... anything interesting for a buck or less. The potential downside of some of these books is that they might be decades old and the ideas might be debunked by now.  This exercise question may be answered in a 1993 reprint of "The T-Factor Diet" by Martin Katahan, PhD, the director of the Vanderbilt Weight Management Program at Vanderbilt University.  In this book, his theory is that you don't gain weight from eating carbs, only from eating too much fat... which I don't quite buy.  But this is what he wrote about exercise."

"AN INCREASE IN EXERCISE TIME OR INTENSITY CAN LEAD TO A BRIEF GAIN OF A FEW POUNDS."

"If at any time you get turned on and suddenly increase your exercise time or intensity a significant amount, say, by 50%, you may gain a couple pounds overnight. This will be gone in a matter of one or two days. It occurs because a sudden increase in exercise-- increasing your walking from 3 to 4 1/2 miles on a weekend hike, for example-- will cause your exercised muscles to take in an extra load of glycogen from subsequent meals. Since glycogen is stored in 3 to 4 parts water, it means considerable weight gain. I gained two pounds overnight when I took my first 6-mile run after being accustomed to only 2 or 3 miles per session. Similarly, if you develope any aches and pains, accompanied by any inflammation of muscles or joints, it means a gain in water weight since the inflamed area will retain some water."

Katahan says that carbohydrates are stored in the muscle as glycocen for ready use when you need it.

I don't know if exercising less causes your body to store less glycogen. But it does sound like what happened to you, dirtpupfc.

I want to reread this section of Katahn's book because he devotes discussion to various things that can shift the fluid balance in your body, causing fluctuations. He says don't bother to weigh yourself more than once a week, unless you have a scientific interest in tracking your fluid fluctuations.  I think it helps to track it day to day, so you get more relaxed about fluctuations... if you continue to eat the same calories, and exercise about the same, the fluctuations always correct. If you weigh in only once a week, it might be the very day you have some weird uptick, and you think you are plateauing or gaining.  If you weigh in every day, and take an average for the week, you get a much better picture of what is going on. 

I don't know about you, but my digestive system (at my 200 lbs weight) can carry at least 2 lbs of food matter.  My body can probably carry +/- 2 lbs of water depending upon salt intake, as well.

When I go on a diet, I don't expect to get consistent losses until I have been on a constant caloric intake for 3-4 days.  It takes that long for your digestive system to start carrying a consistent amount of food, at the new intake rate.

If you did some exercise, perhaps you drank some energy or electrolyte drinks?  Many of them have artificially high levels of salt to keep your bodily fluids up.  That could easily explain your 2 lbs gain.  Then, all that water came off ~ and maybe about 4 lbs of that water, and you had a 2 lbs loss.

I don't know if this helps, but I've found over the years that my body adapts to a steady amount of either exercise or food; that is, if I consistently eat the same amount and type of calories every day, I will eventually hit a plateau.  Ditto with exercise.  That may be why interval training is so effective.

 Weightwatchers has an offshoot program, the Wendie plan, which came about to combat this.  It basically juggles your weekly calories into uneven amounts each day, with a peak day; that way your body isn't able to effectively adapt.  After your one (relatively) high calorie day, you WILL show a weight gain; however, over the week as a total, you will see a more effective loss.

 

Just a thought.

I've noticed this with myself too. Was out on my bike 3 hours on a road today (about 40 miles all told) and will weigh more.

 I'm a biologist, so let me try to address this --

 First, water retention. As you exercise, your blood moves into your muscles with greater volume and that will stay for hours after you finish. You will "retain water" because you have more volume open in your body to hold it. That's why I tank up on water before I go on a ride, so I'm not thirsty in the first hour as my blood starts to move int the peripheries.

 Second, the microinjuries that you inflict on your muscles (we all do) will also have retrained water over the interim and slowly lose as your muscles move back to normal.

 Just my impression. Never mind the fact that our digestive systems slow down w/exercise and we retain bulk as someone else said up there...

  

Thanks all for the thoughts on this topic. It seems water and nutrients retained by the muscles are the leading candidates for explaining this phenomenon. The comments on microinjuries and other causes of water retention were also interesting.

Guess we'll just have to keep the faith that exercise is helping, even if it may not look that way the morning after.

On the "when should I weight myself" front, I'm in the weigh every day club. I'd rather shrug off the odd increase of a pound here or there, rather than place all my bets on a cooperative Friday or Monday weigh-in. I think the weight loss trend line here at CC is a good way to look at things. Even on days when my weight ticks up for whatever reason, the overall trend can continue in an encouraging direction.

Thanks again for the discussion.

This thread makes me feel better! I have been worrying in the back of my head all day about what might be going on with me. I usually get consistent fairly light exercise, long brisk walks, moderate bike rides... Then this past weekend my husband and I decided we should really be trying to push ourselves more if we want to get in shape for backpacking etc... and went on a hard hike everyday Sat-Monday, then last night I went on a 1.5 hr really hard bike ride. My leg muscles are soooo sore and tired and have been all weekend (taking today off!) but Sat was the last morning I saw any weight loss, when I usually see a little something every day (lots to lose, dr supervised so don't get on me about losing too fast :P)
Now I'm really curious to see what the scale will say tomorrow or the next day. Bodies are weird and complicated!

I second the retained water due to sodium. I've dropped six pounds in two days after feeling "sodium" stiffness in my joints by drinking a lot of water.