While most people’s gym routines differ – I, for one, have always been an elliptical girl and hate the stationary bike – it’s safe to assume that almost everyone incorporates a “cool down” into their cardio program. After running for 30 minutes at 7 miles per hour, you’ll knock your speed down to 3 and spend five minutes jogging or walking before you hop off the machine. Many pieces of gym equipment even include a 5-minute cool down automatically, tacking it on to the end of your desired workout. All of this is supposed to prevent soreness or muscle damage and relieve strain on the heart.

According to University of Texas physiologist Hirofumi Tanaka, however, there’s no proof that a cool down has any positive benefits on the body. “Everyone thinks it’s an established fact, so they don’t study it,” he said in a recent New York Times article. The article notes the ambiguity of the concept as a whole, noting that it’s not even clear what a cool down is supposed to be or how long it should last.

Apparently, the cool down became standard gym practice after it was reported that muscles become sore after exercising due to the accumulation of lactic acid. This theory has been reported false, leading people to believe that reducing the intensity at the end of a workout (which was supposed to let the lactic acid dissipate slowly) is unnecessary. The article does note, however, that blood can build up in your legs and feet if you stop running (or biking or ellipti-cizing) shortly, making dizziness or even fainting a possibility.

The article adds that because lactic acid has been discovered to be beneficial, it might be better not to cool down. A study of a group of cyclists showed that cooling down wasted the lactic acid; when they just stopped without reducing their speed gradually, the lactic acid was turned into glycogen, a muscle fuel.

So what does this mean? It means that you don’t have to waste that extra ten minutes at the gym cooling down. In fact, for better results, it means that you shouldn’t. Finish your desired workout, grab your things and head home. Then use that extra time for something more productive, like studying, making a healthy snack… or stalking your crush on Facebook.

There are a multitude of factors, from water consumption to plain old hormones, that can artificially – and temporarily – affect that ever important number on the scale, anywhere from 1-5 pounds in a day.

#1. Water water water.

Water can affect your weight in a couple of ways: drinking too much, and not enough. As a substance, water is pretty heavy, so if you drink a couple big glasses, you’ll see an immediate impact on your weight. On the other hand, dehydration can also lead to a higher number, because it causes the body to retain what water it does have (it thinks there’s a draught or something?). Our bodies are made of 60% water, so any changes in that arena are going to have a noticeable impact overall.

#2 Food

This one seems so obvious, but people sometimes forget that food weighs as much in your stomach as it does on your plate, at least initially. Take that into account when you step on the scale, or better yet, wait ’til you’ve digested before you get anywhere near it.

#3 Aunt Flo

You know how you feel bloated and heavy right around your period? It’s because you are. Hormonal shifts and surges also make your body hold onto water, and we’ve already covered how much water can add up. Exercise, drink plenty of water, and your body will flush it out in due time.

#4 Salt

Going heavy on the salt makes your body hold onto water for dear life which, as we already know, makes us weigh more. This gets especially tricky to control, as most convenience foods, prepared foods, etc., already have a lot of sodium in them, and if you add salt on top of that…well, you may be in for a little surprise next time you step on the scale.

#5 Glycogen

Glycogen is energy stored in your body, in muscles and in your liver, and comes packed with 3-4 pounds of water. If you don’t eat enough carbs during the day, these stores get tapped and the supply will shrink, resulting in a small weight loss. This will increase your appetite, and your body will slowly right itself as you eat. Glycogen and the accompanying water can account for a shift of up to 2 pounds in weight every day.

So, there you have it, the top 5 reasons your weight can fluctuate on any given day. Remember, a pound of fat is 3500 calories. You would have to consume 3500 calories MORE than you burn off in a day, and you burn a good many just by, you know, living. Add in any activity at all and you up that furnace. It’s almost literally impossible to gain a pound overnight, let alone 5. Unless you regularly eat tubs of Crisco every day, chances are, your culprit is one of the above. For this reason, doctors and nutritionists often recommend markers other than a scale to monitor your weight, such as energy level, or a particularly stiff pair of jeans. These things will give you a much more honest answer than your fickle bathroom scale.

If you are going to weigh, try and be consistent with when and how you do it. If you stick to the same time of day, amount of clothing, etc., you’re more likely to get a weight that’s at least relatively accurate. So next time you get a nasty shock, take a breath, think it over, and consider that maybe you’re doing just fine.