Because each type of energy-rich organic molecule that we ingest—whether protein, carbohydrate, or fat—stores a different amount of energy, it’s not only how much we eat but also what we eat that contributes to weight gain. We are more likely to gain weight from a pound of ice cream than a pound of veggies, for example, because ice cream contains more fat—and therefore more Calories.
Some scientists have used this fact to argue that there must be some factor other than small portion size that explains why the French have remained relatively thin. The French may eat less, but they are also world renowned for their love of buttery, creamy sauces, dense desserts, and fatty meats. If the French load up on fat, which has more Calories, how do they manage to keep the weight off? Research such as Rozin’s suggests that it may still have to do with portion size: the French may eat fatty foods, but they do so in moderation—savoring smaller amounts of these rich dishes than their American counterparts.
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How do the French manage to eat smaller portions? In France and many other European countries, small is the cultural norm. The French don’t supersize, and they are less likely to buy in bulk. So the opportunity to eat more may not exist in the first place. Research by other investigators has shown that a person presented with a bigger package of, say, M&M candies will take more from it than when presented with a smaller package. A 2007 study led by Jennifer Fischer at Baylor College of Medicine, for example, found that preschool-age children consumed 33% more Calories when the portion size of the meal was doubled. This behavior combined with meals made with a high ratio of energy-dense ingredients—oil, butter, and sugar—is a significant contributor to childhood obesity, these researchers concluded.
Or it may have to do with the way the French eat; not only do they eat smaller portions at each meal, they don’t snack, they don’t opt for second helpings, and they don’t skip meals. Mireille Guiliano in her book French Women Don’t Get Fat described how she gained 20 pounds during her 5-month stay in America. She snacked, she drank a lot of soda, and she ate standing up without really focusing on her food, she wrote. Guiliano found that she had forgotten how to slow down and enjoy the taste of food the way she used to in France, and so she compensated by eating larger portions. Part of her diet plan when she returned to France, she wrote, was quitting in-between-meals snacking and re-acquainting herself with the French culture of eating, which involves slowing down and savoring each bite.
Indeed, evidence suggests that the French do eat more slowly. In his study, Rozin compared the average time people spent eating at McDonald’s in Paris and in Philadelphia. In Paris, the average time of the meal was 22 minutes; in Philadelphia, only 14. While scientists don’t know for sure how longer meals help people eat less, they speculate that taking it slow may help people enjoy their food more and recognize when they are full.
In addition to having different eating habits, the French may also be more active than Americans. Walking, biking, and taking public transportation to work are more common in Paris than they are in many parts of the United States, which is geographically spread out and more heavily dependent on cars.
However it is that the French remain slim, one thing is clear: they weigh less because they either eat less or burn more Calories. The only way to gain weight is by taking in more Calories than we expend through energy-using activities. In other words, our waistlines obey the principle of conservation of energy (see Chapter 5): energy is neither created nor destroyed but merely converted from one form into another. If more food energy is taken into our bodies than is used to power cellular reactions and physical movement, the excess (minus what is released as heat with every energy conversion) is stored as fat.