時尚雙語:爲什麼人的體重在晚上重一些？

I sometimes seem to gain about 10 pounds during the day. Is it water retention?

Q: I weigh myself both in the morning and again at night. In the morning I'm around 193 pounds, but in the evening, my weight sometimes hikes up to 204 pounds. I use the same scale and weigh in the nude, so I feel like my readings are accurate. My friend says that I have a water-retention problem. What can I do to treat this?

A: It's normal for body weight to fluctuate widely throughout the day. It's likely that your weight in the morning, and especially after you've used the bathroom, is at its lowest since you have probably not consumed any food or water for the past 12 or so hours.

How much and what kind of food and fluids you've consumed, as well as how much and how often you've evacuated, and even how much you have sweated all play a role in the pounds that register on the scale at any given point during the day.

Be careful not to mistake the increased scale weight as a conclusive sign that you are gaining or losing weight because going by pounds alone can often be misleading. While most people cite one number as their current body weight, it may be more realistic to cite a range, since the number does fluctuate daily. Most weight-loss programs advise to weigh at the same time of the day to try to minimize this variation. But still, if you were to weigh yourself every two or three hours you are likely get a whole range of weights, and here's why:

You can even sit in a sauna and sweat off five pounds, but that doesn't mean that you've lost five pounds of body fat. In fact, you'll gain that 'weight' right back after you replenish the fluids you sweated out. Water is retained and lost throughout the day and while it may be contributing to your varying readings, these fluctuations are most likely normal, and not necessarily the problem that your friend suggests. (If you have signs of bloating, check with your physician, however.)

If you eat a meal that consists of lots of plant foods like beans, grains, veggies and fruit, the food might weigh quite a lot because of all the fiber and water in it. On the other hand, you could eat the exact same amount of calories in the form of processed high-carb or high-fat foods and since this food is very condensed (much of the fiber and water is processed out of it), it's very light. If you ate the more healthful food you might take in a couple of pounds of actual food that would actually make you seem heavier if you weighed yourself after eating it. The processed item such as a fluffy, light croissant may not register as much extra scale weight at all even though it's very high in calories.

So does the heavier-weighing food make you fatter? Not at all. Here's why: The body gains weight from accumulating more stored body fat by eating more calories than are expended over time. (You can also gain more weight for other reasons such as increased muscle, but you would need to be doing progressive, heavy resistance training and eating more calories over time.)

When you eat a large meal, and if it's an unprocessed, plant-based meal, it's likely to be lower in calories, even if it has greater volume. Check out this comparison from the book Picture Perfect Weight Loss (Grand Central Publishing, 2003) by chiropractor Howard Shapiro. One small muffin is around 720 calories, and a huge platter consisting of an entire pineapple (that weighs several pounds), half a melon, half a papaya, plus two pears, some grapes, kiwi and two small whole-wheat rolls are also 720 calories. Not only would it would be nearly impossible to eat the healthful meal at once (who can eat an entire pineapple without feeling stuffed?), if you managed to even eat half of this, you would have ingested a pound or two of food, compared to a few ounces by eating the muffin.

So after eating this plant-based meal, you would temporarily weigh more while the food is going through your digestive system. That doesn't mean you are heavier, though, because it's the caloric load that ultimately leads to excess body fat. In reality you might only be able to eat about 400 or 500 calories worth of this healthful meal, even though you ate much more in terms of volume of food. Most of the fiber and water in the plant-based meal is calorie-free and would be excreted out, NOT turned into extra body fat.

Another example in the book compares two 400-calorie options: a high-fat choice such as three small ribs or one egg roll, or a large meal consisting of brown rice, vegetable soup, a fortune cookie and Chinese-style broccoli and shrimp.

Chances are that you'd not feel full eating only one egg roll or a few ribs. One could easily eat double, triple (or more!) than the 400-calorie serving shown to make a meal. So you could easily take in 800 to 1,600 calories at one sitting choosing the high-fat options. In comparison, it might be difficult to eat the entire healthful meal shown. But even if you did, it would consist of only 400 calories. So you'd feel satiated, but you still be dieting because you are controlling your caloric intake with these plant-based foods that are high in both fiber and water.

The major point to keep in mind is that, while weight is important, it is not a total reflection of your body composition such as the amount of body fat and/or muscle that you have. When losing large amounts of weight, the scale is a useful tool to gauge the change. But avoid getting too nit-picky with daily readings, and look for trends over time. If you have access, try getting your body composition measured, either through a DEXA scan at your doctor's office, or by using body fat calipers by an experienced trainer at your gym. An underwater weighing tank in the exercise physiology department at a local university is another option (some gyms occasionally offer measurements taken in portable tanks). It's also important if you are losing weight to make sure to include some resistance training in your routine so that you can minimize the amount of muscle loss that inevitably accompanies weight loss.

在白天，有時我似乎增加了10磅的體重。是不是因爲含有更多的水?

Q:我在早上和晚上各稱一次體重。在早上，我大約193磅，但在晚上，我的體重有時會上升到204磅。我使用相同的磅秤，同樣是裸體稱，所以我覺得讀數應該是準確的。我的朋友說我有保水的問題。我應該怎樣做？

A:體重在一天中有波動是正常的。早上尤其是剛洗完澡後，體重是最低的，因爲你可能已經12個小時沒有進食或喝水。

進食的數量和種類，進食消耗的多少與頻度，甚至出汗的多少，這些都決定了你在白天的體重。

不要因磅秤上體重的變化作爲增加或減少體重的結論，因爲幾磅重的變化會誤導人。人們經常舉出一個數字作爲其體重，可能舉出一個範圍更實際一些，因爲體重的浮動。大多數減肥計劃建議每天的同一時間稱量體重，以求減弱這種變化。但是，就算是你每兩、三個小時稱一次，得到的也是一系列重量，原因如下：

你可以坐在桑拿房裏蒸掉5磅，但這並不是說你減掉了5磅脂肪。實際上，你會重新補充這些體重。在一天中，水會保持或流失，同時你的體重會發生變化，這些浮動是正常的，並不像你朋友建議的那樣是問題。（如果，你有腹脹的跡象，請找醫生檢查一下。）

如果你所吃的一餐中包含大量的植物類食品，比如豆類、穀類、蔬菜類及水果類，因含有較多的纖維和水，食物總量較重。另一方面，你可以吃具有相同熱量的，以高碳水化合物或高脂肪形式存在的食物，因爲它們是濃縮的（大部分的纖維和水被處理掉），所以非常輕。如果你吃了更健康的食物，有可能會吃掉兩磅，這會使你更重。處理過的食物，例如蓬鬆，輕牛角麪包重量並不大，雖然它們含有較高的熱量。

所以，是重量大的食物使你變胖？根本不是。以下是原因：體重的增加是人體攝入的能量超過消耗，剩餘的能量以脂肪的形式儲存起來。（你也可以因其他原因獲得更多的重量，如增加肌肉，但是你得積極一些，沉重的訓練及多吃。）

當你吃一頓未經處理的、以植物爲基礎的大餐，雖然重量很大，所含卡路里比較少。拿這個和Picture Perfect Weight Loss 對比一下。一個小松餅大約含有720卡路里，一個由整個菠蘿（有幾磅重），半個甜瓜，半個木瓜，再加兩個梨，一些葡萄，獼猴桃和兩個小全麥卷組成的拼盤，含有的能量也是720卡路里。一次吃下如上的健康飲食是幾乎不可能的（誰可以吃掉整個菠蘿而不覺得飽？），如果能成功地吃下一半，你可能吃掉了一兩磅的食物，相比較而言，只會有幾盎司的鬆餅。

在吃完這頓以植物爲主的飯後,你的體重會因食物正在通過消化系統而加重.雖然這並不是意味着你真的變重了,但能量最終會增加脂肪含量.在現實中,你只能吃下400或500的卡路里,即使你吃下更大數量的食物.大多數植物飲食中的纖維和水不含卡路里,它們將會被排除體內,不會轉變成脂肪.

書中的另一個例子比較了兩個400卡路里的選擇:高脂肪的選擇,如三個小排骨或一個蛋卷,或一頓大餐,包括糙米,蔬菜湯,幸運餅乾和中國風格的花椰菜及蝦.

事情可能會這樣,你只吃一個蛋卷或幾個排骨不充足.人們很容易就吃下400卡路里的雙倍,三倍(或更多!).所以你可以容易地在800至1600卡路里中選擇高脂肪.相比之下,可能很難吃下整個健康餐.即使你做得到,它只含有400 卡路里.你會感到吃飽的,你仍然在節食,因爲你進食含較多纖維和水的植物性膳食,控制了能量的攝取.

你要謹記,儘管稱體重很重要,但它無法完全反映身體的組成,如身體脂肪和/或肌肉含量.當失去大量重量時,磅秤是一個有用的工具來判斷變化.但是避免過分講究讀數並尋找趨勢.如果有機會,嘗試身體成分測試,要麼在醫生的辦公室通過掃描儀,要麼在健身房由有經驗的教練使用脂肪卡鉗.當地大學生理學系的水下稱量桶是另一種方法(有些體育館偶爾也會提供便攜式罐體).還有一點也很重要,如果你正在減肥,你要做一些訓練,儘量減少肌肉的損失.