Studies consistently show that nighttime eating does not actually cause weight gain if you stay within your body's daily caloric needs. The British Medical Journal recently put the myth to rest in an article in which they reviewed the results of various studies on the topic of night-time eating and weight gain. After looking at numerous clinical studies throughout the world, they concluded that there is no link between eating at night and weight gain. The American Dietetic Association agrees and emphasizes that it's not the timing but the amount being eaten that can cause weight gain. The fact is that your body will store any extra calories as fat if you take in more calories than you burn in a day, regardless of the time of day in which you consume those excess calories.
Where some people do get into trouble with eating late at night is if they binge and take in more calories than they need in a day. This often happens when people restrict their intake too much during the day. If you find that you're ravenous at night, you probably aren't getting enough calories throughout the day. This is why severely restrictive, extremely low-calorie diets backfire--they are too difficult to maintain long-term and ultimately are unhealthy because they bring your metabolism to a screeching halt. Your best bet is to eat portion-controlled meals consistently throughout the day, never going more than 3-4 hours without eating. Try consuming 4-5 smaller meals throughout the day instead of having 3 large meals. This will provide you with consistent fuel and prevent you from feeling famished in the evening, when you're likely to reach for quick, high-calorie foods.
Another reason people who tend to eat more of their calories late at night can gain weight is because they are "mindlessly eating" while sitting in front of the television or computer. Often they start eating around dinner time and then continue to graze until they go to bed. People who do this aren't truly hungry but rather are eating out of habit, boredom, stress, or fatigue. People also tend to make poor food choices at this time--chips, ice cream, desserts, etc. This causes them to take in more calories than they need, but it has nothing to do with the time of day.
The bottom line: Your body does not process food differently after it gets dark outside. Eating too many calories, regardless of the time of day in which you do so, can lead to weight gain. It all comes down to balancing calories in with calories out (through reducing caloric intake or increasing physical activity).
Kari Hartel, RD, LD is a Registered Dietitian and freelance writer based out of St. Louis, MO. Kari is passionate about nutrition education and the prevention of chronic disease through a healthy diet and active lifestyle. Kari holds a Bachelor of Science in Dietetics from Southeast Missouri State University and is committed to helping people lead healthy lives. She completed a yearlong dietetic internship at OSF St. Francis Medical Center in Peoria, IL, where she worked with a multitude of clients and patients with complicated diagnoses. She planned, marketed, and implemented nutrition education programs and cooking demonstrations for the general public as well as for special populations, including patients with cancer, heart disease, diabetes, Alzheimer's disease, obesity, and school-aged children. Contact Kari at KariHartelRD@gmail.com.