Every few months, a new study purports to prove that a calorie is a calorie is a calorie, and that the only way to lose weight is to burn more than you take in.

But veteran dieters know something that some researchers apparently don't: Certain foods seem to fuel the appetite like pouring gasoline on a fire. Some people find that once they start eating bread, cookies, chocolate -- or leftover Easter candy -- they lose all sense of fullness and find it difficult to stop.

That's the concept behind 'The Skinny,' a new book by Louis J. Aronne, director of the Comprehensive Weight Loss Program at NewYork Presbyterian Hospital/Weill Cornell Medical Center. 'It's true that a calorie is a calorie,' Dr. Aronne says. 'But what that doesn't take into account is how some calories affect what people eat later on.'

After 23 years of treating patients, Dr. Aronne has concluded that refined carbohydrates and foods with high sugar and fat content promote what he calls 'fullness resistance.' They interfere with the complex hormonal messages the body usually sends to the brain to signal that it's time to stop eating. People feel hungrier instead.

This happens in part because refined carbohydrates raise blood-sugar levels, setting up an insulin surge that drives blood sugar down again, causing rebound hunger. That insulin spike also interferes with leptin, the hormone secreted by fat cells that should tell the body to stop eating. Obese people have loads of leptin, but it either doesn't get to the brain, or the brain becomes resistant to it.

Other researchers have described similar phenomena. An article in this month's Medical Hypothesis argues that for some people, refined foods with high sugar and carbohydrate content can be just as addictive as tobacco and alcohol.

Eating foods high in protein, vegetables, fiber and water have the opposite effect, Dr. Aronne says. His plan recommends revising what you eat, one meal at a time, to restore your sense of fullness:

Breakfast: Loading up on lean protein -- ideally from egg whites or a protein shake -- in the morning reduces hunger all day long. Eating muffins, bread, sweetened cereal and juice does the opposite. A study of 30 overweight women at Saint Louis University School of Medicine found that those who ate eggs for breakfast consumed 140 fewer calories at lunch, and ate less for the next 36 hours, compared with women who ate bagels in the morning.

Lunch: Some dieters try to cut calories by skipping this meal. But going more than five hours without food causes hunger hormones to rise and fullness hormones to drop, and sends more of the calories consumed at dinner straight to fat cells. Dr. Aronne recommends starting lunch with a salad, then more vegetables, and then lean protein. Skip the cheese, bacon and creamy dressings, he advises. Using vinegar alone will cut your appetite and slow the rise in blood sugar.

Dinner. The end of the day is fraught with temptation. Obese people consume significantly more calories at dinner than slimmer people. Here, too, load up first on salads, clear soups, or high-protein appetizers like shrimp cocktail, then have a lean protein main course. Eating bread before dinner makes people lose their sense of fullness and eat more, Dr. Aronne warns. Alcohol makes it worse by lowering your resistance and promoting fat storage.

Not everyone agrees that consuming more protein cuts appetite. Harvard School of Public Health's Frank Sacks led a study published in the New England Journal of Medicine that compared 811 overweight adults on four diets with varying levels of protein, fat and carbohydrate. 'We found absolutely no difference in their satiety and hunger levels,' Dr. Sacks says.

All the groups lost similar amounts of weight. That's not surprising, other weight-loss experts say, since there were only modest differences in their fat, protein and carbohydrate intakes, and many participants didn't stick to their plans.

To be sure, if you eat as Dr. Aronne suggests, you'll consume fewer calories overall. The point is, eating protein early in the day may make it much easier to cut down.

每隔幾個月就會有一項新研究試圖證明卡路里就是熱量，減肥的唯一途徑就是讓卡路里的消耗量超過攝入量。

但有經驗的節食者知道一些研究人員顯然不清楚的事情：某些食品似乎能夠增進食欲，就象火上澆油一樣。一些人發現，一旦他們開始吃面包、曲奇、巧克力──或是復活節剩下的糖果──他們的飽足感就會蕩然無存，難以停嘴。

這就是紐約長老會醫院/威爾•康奈爾醫療中心(NewYork Presbyterian Hospital/Weill Cornell Medical Center)綜合減肥項目主任亞隆(Louis J. Aronne)的新書《瘦身》(The Skinny)中的理論。他說，卡路里就是熱量這話說的沒錯，但這個觀念沒有考慮到一些卡路里如何影響人們隨后的進食。

根據亞隆23年的從醫經驗總結，精制碳水化合物和高糖份和高脂肪含量的食品能夠增進他所謂的“抵御飽足感”。這些食物會干擾人體通常向大腦發出的是時候停止進食的復雜荷爾蒙信息。因此，人就會感覺到更饑餓。

這其中的部分原因是，精制碳水化合物會提高血糖含量，促使胰島素大量上升，再次降低血糖，進而引發饑餓感。胰島素上升也會干擾脂肪細胞生成的瘦體素，這種荷爾蒙本應告訴人體停止進食。肥胖的人也有大量瘦體素，但要么這種荷爾蒙不作用于大腦，要么大腦對此沒有反應。

其他研究人員也描述過類似的現象。醫學期刊《Medical Hypothesis》本月刊登的一篇文章稱，對某些人來說，高糖份和高碳水化合物的精制食品可以像煙和酒一樣上癮。

亞隆說，高蛋白食品、蔬菜、纖維和水則會產生相反的效果。他建議你調整三餐食譜，以恢復飽足感。

早餐：早上攝入精益蛋白質──最好是蛋清或是高蛋白飲品──可以降低一天的饑餓感。食用松餅、面包、加糖麥片和果汁則會起到相反的效果。圣路易斯大學醫學院曾對30個體重超標的女性進行過研究，發現與早餐吃貝果（先蒸后烤的發面圈）的婦女相比，早餐吃雞蛋的女性在中餐時會少攝入140卡路里的熱量，未來36個小時的進食量也較少。

午餐：一些節食者試圖不吃午餐來減少卡路里攝入。但超過5個小時不進食會導致饑餓荷爾蒙上升以及飽足荷爾蒙下降，將更多晚餐時攝入的熱量直接轉化為脂肪細胞。亞隆建議午餐先吃份沙拉，再吃較多的蔬菜，然后是精益蛋白質。他建議別吃奶酪、培根和奶油沙拉醬。喝醋能夠降低食欲，并延緩血糖濃度的上升。

晚餐：每天的最后一餐總是充滿誘惑。與身材較瘦的人相比，肥胖的人晚餐明顯會攝入更多熱量。同樣的，晚餐也先吃沙拉、清湯或是雞尾酒蝦等高蛋白開胃菜；然后再吃精益蛋白質的主菜。亞隆警告說，在晚餐之前吃面包會讓人飽足感下降，加大食欲。酒精則會讓情況更糟，因為這會降低你的抵制力，加速脂肪存儲。

并不是所有人都認同消耗更多蛋白質可以降低食欲的觀點。哈佛大學公共健康學院(Harvard School of Public Health)的薩克斯(Frank Sacks)領導了一項研究，其論文刊登在《新英格蘭醫學期刊》(New England Journal of Medicine)上。這項研究對參加四組節食療法的811名成年肥胖者進行比較，每組所采用的節食療法蛋白質、脂肪和碳水化合物含量各不相同。他說，我們發現他們的飽足和饑餓程度沒有任何區別。

參加研究的四組患者減去了類似的體重，其他減肥專家說，這并不令人吃驚，因為他們的脂肪、蛋白質和碳水化合物攝入量只有細微的差別，而且很多參與者并沒有堅持減肥計劃。

當然，如果你像亞隆建議的那樣進食，總的來說你就會攝入較少的熱量。關鍵是，在每天早間食用蛋白質或許會比較容易減少熱量攝入。