The answer may be simpler than you think.
As many study abroad students can testify, Europeans do considerably more walking than Americans. Even on the confines of smaller college campuses here in the states, students can be seen driving from their dorms to the academic buildings just to avoid a 15 minute walk. In many European cities, including Paris and Florence, walking or biking to a destination is the main mode of transportation for locals. Walking to the grocery or a restaurant, or out to the pharmacy or the bus station can easily provide a few miles of easy exercise.
Many doctors even advocate walking over jogging or running for patients looking to incorporate a little extra physical activity into their day. Walking places less stress on your joints than the two more intense exercises, resulting in fewer injuries and long-term damage. Yet a couple-mile walk still provides adequate exercise for the body. Managing to take the stairs at work or make the 15-20 minute walk to the post office, grocery, or classroom (where safe pedestrian walk-ways have been provided) could mean all the difference to your overall goals - further boosting a fitness plan that incorporates a healthy diet and regular physical activity.
Taking regular walks in conjunction with eating smaller portions at mealtime and drinking lots of water have positive effects on overall weight loss. Putting your food on smaller plates can sometimes help with portion control, tricking your brain into thinking you're eating a lot more food since your plate is full. Growing up it's likely you heard the 8 x 8 rule for drinking water "Drink at least eight 8-ounce glasses a day". The Institute of Medicine determined even more precise amounts to be consumed, as well as the differences between genders, placing adequate daily intake at 3 liters (13 cups) for men, and 2.2 liters (about 9 cups) for women. Keeping your body well-hydrated can have a positive impact on your body's weight loss by ensuring all of your body's essential functions run at their optimal levels.
Many students who studied abroad in Europe experienced this gradual weight loss to shed a total of 10 or more pounds upon their return to the U.S.. In my own personal experience while studying abroad in Florence, my inevitable daily walks on my way to class, running errands, or simply exploring the city, combined with my higher water intake and smaller portions at mealtimes, resulted in a loss of 30 pounds. My two other American roommates also reported weight loss numbers around 15 pounds.
We discovered just how all the Italian women around us stayed so skinny- the lack of fast food in our diets, a lot more water, and just a little walking.