Why do I gain 4lbs after intense exercise?

November 2, 2006 10:43 AM

I'm actively losing weight but always seem to gain 3-4 lbs following intense exercise days.

I'm losing weight by trying to take in about 2000 or so calories a day. I'm not strictly counting, more like approximating, but things are going well so far. I'm a lot more calorie-aware of what I eat now(check out my last question for info).

Each day, I weight myself first thing in the morning.

Here's what I'm noticing-My weight gradually lowers, or steadies, as the days go on. Then, after days with activity (2+ hour bike rides, 1 hr pickup basketball), my weight creeps up about 4 or so pounds. This is fairly consistent with the day after exercise. Sometimes, on post-exercise-days, I'm a lot hungrier than normal(which I would expect). A few days later, those 4lbs are gone and i'm back on my downward trend(yay!).

Now when I'm riding, I'll drink 2 16oz bottles of cytomax(90 calories per bottle), maybe a clif bar. I eliminated gatorade and 'carbo loading' and huge post-ride meals. When I ride, its at tempo, or a canyon climb-no LSD for me. I'm working at 80-95% MHR for those 2 hrs.

In short, there is no way in hell that I'm eating an additional 14,000 calories or so in 1 day to put that weight back on. Dont forget that I just burned 3000 or so calories on that bike ride.

I'm pretty sure that those fluctuations are water but I'd love an explanation. Is this normal? This only happens the day or two after intense exercise.

Also, when does the body actually 'burn' the fat? I know that you need to have a 3500 calorie deficit to burn 1lb fat. When does this take place? Does it happen in real time, or is there some 'batch job' that runs (sorry!) that figures the deficit and lets go of the fat.

posted by neilkod to health & fitness (24 comments total)

Are you drinking plenty of water, all the time? 32oz for a 2+-hour bike ride does not sound like enough.

The interwebs tell me that when you're not sufficiently hydrated, your body stores lots of extra water.
posted by trevyn at 10:56 AM on November 2, 2006

I don't have a scientific explanation, but on the weight loss related message board I frequent, most of the people who are intense exercisers do agree that you retain water after intense workouts. Also people who are just starting a workout regime tend to "gain" a few pounds that appears to be water weight.

As with any water retention, drinking even more water on heavy exercise days should help the bloat. It's possible that what you're drinking/eating on those days might be higher in sodium which can cause you to retain the extra water.
posted by tastybrains at 10:57 AM on November 2, 2006

I drink water all the time, especially throughout the day. Lots of it. Sometimes I refill my bottles with water if I go through the cyto quickly.
posted by neilkod at 11:01 AM on November 2, 2006

When your blood sugar level is low and you've been exercising with an elevated heart rate for over 20 minutes, you're burning fat. How much depends on alot of variables (how much you've slept, how strenuous the exercise, how conditioned you are etc) but following those two conditions will do the job. As for your weight going up after a day of strenuous exercise? That happens to me too sometimes - when I haven't been drinking enough water. The body will hoard fluids as a survival mechanism. I also tend to be heavier after a day of strenuous exercise if I've carb-loaded, even a little bit. Carbs=glucose=glycogen and that goes straight to muscle stores. It's not bad weight however, it's good because glycogen is important for muscle preservation.
posted by dropkick at 11:01 AM on November 2, 2006

Could it also be that after you finish your workout, you're thirsty, and so you drink a lot of water after the exercise? This could be especially relevant if you don't drink enough water from a general, day-to-day standpoint. I think you're most likely right that it's water weight, and if, on the whole, you're moving in the direction you want to (weight-wise), I wouldn't worry about this.
posted by HighTechUnderpants at 11:02 AM on November 2, 2006

first of all: axe the cliff bar. you could eat a full lean cuisine meal for the same calories.

second: stop weighing yourself every single day. you're driving yourself nuts. do it every third day. you already have a good intuition when it comes to your having "been good or bad" - don't let the scale freak you out.

it's probably water anyway. you are not gaining fat. at the very most, it's muscle (muscle is heavier than fat). you will shed the water within 24 hours anyway. so repeat after me: do not get onto the scale ever day.

mmmmkay?
posted by krautland at 11:19 AM on November 2, 2006 [2 favorites]

every day.
posted by krautland at 11:21 AM on November 2, 2006

krautland-you try bring a lean cuisine and a microwave on a road bike! I know I need to take in *some* calories while on the bike.
posted by neilkod at 11:23 AM on November 2, 2006

I've heard that your muscles need 4 molecules of water to store one molecule of glycogen, but I'm having trouble finding a link. Therefore, it would make sense that after working out intensely, your body readies itself for another expenditure of energy by storing more glycogen, and hence, more water. This would result in increased water weight, which would decrease as your body used up the glycogen.
I've also heard that this is why the atkins diet works so dramatically--you're not eating glucose, so therefore you're not storing glycogen, and you lose a ton of water weight.
posted by chelseagirl at 11:25 AM on November 2, 2006

Cytomax: 5oz per 15 minutes at about 100 calories per 16oz (scoop, really). Clif bar at 200 calories. Ride at 1500-2500 calories. Looks like you're doing fine.. don't sweat water weight, just check your belt. :) You'll burn less calories from existing fat at 80-90% MHR but you'll burn more overall calories, plus build more muscle which raises your Basal rate. Bonus: burning calories for free while you sleep.

I'd rather a Clif Builder's Bar over a Lean Cuisine any day, anyway. Yuck.
posted by kcm at 11:30 AM on November 2, 2006

Yea, I agree with krautland...don't weigh yourself everyday. Working out is about you feeling healthy and doing your body good. Your weight is just a number, and can fluctuate day to day based on so many factors.

Weighing yourself everyday encourages bad habits and is just stressful. Don't live and die by the number- focus on how you feel.
posted by unexpected at 11:40 AM on November 2, 2006

Your weight will fluctuate a few pounds over the course of a day or two for various reasons, including fluid retention, recent activity, eating, etc. This is normal. I agree with all of the other posters who say that you'll make yourself nuts weighing every day. It's counterproductive to the progress you're trying to make. As long as you're still on a downward trend, you're doing what you're supposed to be doing. Stop worrying so much and just enjoy your new healthy lifestyle.
posted by decathecting at 11:49 AM on November 2, 2006 [1 favorite]

Dieting combined with heavy exercise can have the paradoxical effect of making you lose fat without actually losing weight. You'll be building up muscle and bone mass, which are more dense.

Of course, that happens over a period of weeks, not over a period of hours.
posted by Steven C. Den Beste at 12:01 PM on November 2, 2006

neilkod: do you really have to eat while on the bike?

I can barely manage to gulp down a splash of water once I get going. [krautland runs 5 miles every evening]
posted by krautland at 12:23 PM on November 2, 2006

Absolutely keep weighing yourself every day. The problem isn't that you're weighing yourself, and it isn't that you're gaining weight, it's that you're looking at too small a snapshot to see what's going on in your body. What you should be doing is tracking your average weight loss with daily weigh-ins measured plotted on a graph. This allows you to visualize what's happening, and does away with artifacts like the one you describe. This guy has an excel spreadsheet that does the calculations for you.

Why do you appear to be gaining four pounds the day after? Who knows? Maybe you don't have the same kind of bowel movements after exercise, maybe it is something to do with water retention. Regardless, what's absolutely certain is that you aren't gaining four pounds of either weight or muscle after working out once. The most you might do by eating more on those days is slow your subsequent weight loss, but this is unlikely given the dynamics of metabolism and the actual calories burned.

Switch to a running average, pay attention to whether the line is headed up or down, and you'll be fine.
posted by OmieWise at 12:25 PM on November 2, 2006

Omie-I'm doing the same thing using eatwatch.prc on my treo! I am most certainly following the running averages
posted by neilkod at 12:29 PM on November 2, 2006

Yep, the exact same thing happens to me too. I'm convinced it's water weight. It's often 3-4 pounds for me too. It was really frustrating, but I'm used to it now.
posted by pazazygeek at 12:32 PM on November 2, 2006

I agree with all the above posters that the day to day weight fluctuations are water. Ignore them (the changes, not the posters).

As for when the fat is burnt, it more or less happens in real time. When you exercise, carbohydrates and fats are broken down and combined with oxygen to release energy. The waste products of the reaction are water and C02 some of which leaves your body more or less immediately as you breathe and sweat.
posted by justkevin at 12:40 PM on November 2, 2006

I use www.physicsdiet.com to keep track of my average weight. I weigh myself every day and I don't get discouraged if it's up unless the trend line is headed the wrong direction.

Weighing yourself less often is still just as prone to random fluctuations; doing it every day at least gives you a good dataset from which to calculate the trend. I've definately had streaks of days where I've been above the trend line, followed by a big plummet which didn't affect the overall slope.
posted by metajack at 1:43 PM on November 2, 2006

Post-exercise weight gain is actually associated with drinking too much water during your exercise session, so don't be so quick to assume dehydration like posters upstream suggested.
posted by footnote at 5:09 PM on November 2, 2006

Seconding metajack's recommendation to weigh yourself every day but only concern yourself with long-term moving averages. It takes some getting used to, to be certain - the whole "I ate 1,600 calories yesterday and ran three miles, but still show an uptick on the scale, WTF?" can be demoralizing - but if you can convince yourself to disregard the day-to-day fluctuations and instead look towards trend lines, you'll be a much happier camper in the long run. (Or, at very least, not be driven to madness by the day-to-day jitter you're seeing presently....)
posted by youhas at 5:22 PM on November 2, 2006

Lean Cuisine? WTF? Keep looking at the scale but go with the more long term view.
posted by fixedgear at 6:04 PM on November 2, 2006

There's a reason you're not supposed to weight yourself daily, or even every few days...it's not an accurate measure of your body weight and body fat percentage either. Stick to once a week weigh-ins, so only 4x a month. You'll notice the results much more drastically then if you do a day-to-day.

If you drink water all day long, you're probably going to retain a lot of it, even if you're not dehydrated. You eat meals throughout the day so ALSO the food contributes to your elevated weight. Think about it...you might go through 3 pounds of raw food and liquid a day...there's stuff sitting in your intestines too!

I find weekly weighings, when there's the least in my body are pristine to get a good idea of your true weight.
posted by PetiePal at 6:51 AM on November 3, 2006

chelseagirl has the right explanation - it's the water that is lost as the glycogen stores are depeleted.
posted by selfmedicating at 7:33 PM on January 5, 2007