You’ve probably had days where you stepped on the bathroom scale and gained a large amount of weight in a short period of time. This is especially frustrating if you have been actively losing weight, as you can gain in one day what it took five days to lose.
I can dramatically increase or decrease my body weight in a 24-hour period. This isn’t all fat, though. Remember, the human body is mostly water, so you can gain or lose water in large amounts as both carbohydrates and sodium require additional water to maintain their concentration in the body. In other words, you retain water when more of these molecules are present in the body, and you lose water as they decrease (i.e. on a diet).
Additionally, food caries weight itself, adding or subtracting from your body weight. And even exercise causes a short-term increase in water retention (as your muscles soak up water–which is excreted in a matter of hours).
Long-term weight balance
The desire for weight loss most specifically means a decrease in bodily fat. The most important factor in your long-term fat supply is calorie balance (calories absorbed – calories expended). Interestingly, the weight of food alone does not determine its caloric content. For example, a pound of cucumbers weighs the same amount as a pound of ice cream; but the ice cream has a significantly higher calorie content, contributing more to your fat supply.
Additionally, exercise, while an effective means of expending calories, is not as efficient as consuming calories. Using our ice cream example, it takes only 10 minutes to eat 400 calories worth of the delicious dessert, but it can take at least 40 minutes of full-body exercise to burn it off! And that’s before you even begin to dip into existing fat stores. The biggest contributor to your calorie expenditure is your lean body mass (organs, etc.) so by simply staying alive you will burn calories. It’s how many calories you ingest and how much fat you have on hand that will determine where these calories come from.
Take home message
Try not to get too frustrated at dramatic increases in weight. If you have been progressively losing fat, and your weight suddenly balloons up in a matter of hours, most likely all of it was not fat. Unless you were eating pounds of butter or olive oil; most of it was probably water.
Simply return to a calorie deficit as soon as possible. Don’t cheat because you “already screwed up”. Remember, calories run along a continuum–the more you eat, the more you store, and the less you eat, the more you lose.
Does retaining water affect your physical appearance? You bet. When you’re holding water underneath the skin, it “smooths out” your definition making you look soft; whereas retaining minimal water makes you look and feel “hard” and is what physique competitors refer to as the “dry look”. But this only matters if you’re already lean.
On the subject of cheat days / cheat meals, my philosophy is that there is no such thing. A cruel but true statement:
“What you eat in private shows up in public.”