When You Eat Affects How Much You Eat

---

de Castro, JM: The Time of Day of Food Intake Influences Overall Intake in Humans. J Nutr 134:104-111, 2004.

What is the problem and what is known about it so far?

Obesity is a growing problem in the U.S. It's important to try and understand the causes of obesity to help people prevent and treat it.

The amount of food people eat depends on many different things related to their bodies and minds, as well as to the environment they live in. Earlier studies suggest that peoples' meals tend to get bigger during the course of the day, but the time between meals and their feeling of fullness decrease over the day. In other words, as the day goes by, people tend to eat larger meals and eat again sooner. This may make people more likely to overeat in the evening.

Researchers wanted to find out if the time of day people eat is related to how much they eat. This study was designed to test their idea that eating early in the day would reduce the total amount of food peopleeat in a day.

Who was studied?

The study included 375 men and 492 women with a mean age of 36. The study did not include people if they were dieting, pregnant, breastfeeding, on medication or had alcohol problems.

How was the study done?

The subjects were given a small diary and were told to write down the details of every item they ate or drank for seven days. They wrote down the time they ate , the amount they ate, how the food was cooked, how many people ate with them, and how attractive they found the food. They also rated their feelings of hunger, thirst, anxiety and depression.

For each meal, the researchers measured the food for the amount of energy, carbohydrates, fat, protein, and alcohol it contained. They also measured the length of the meal, how fast it was eaten, the time between meals, and a subject's fullness.

Other measurements of the food and its nutritional content were made at five different times of the day.

What did the researchers find?

The total amount of energy from food people ate differed among the five time periods throughout the day, with peaks during lunch and dinner times (between 10 a.m. - 2 p.m. and 6 p.m. - 10 p.m.). This is a result of people eating larger and longer meals over the course of the day. Food intake increased over the day, but the time between meals got shorter.

What were the limitations of the study?

Because the information was self-reported, the diet diary may not be entirely accurate. The time of day people eat is a significant factor in how much they eat, but there are other important factors as well.

What are the implications of the study?

Eating a large meal in the morning may reduce the total amount of food people eat throughout the day. Eating a large meal in late evening may increase your total food intake during the day.

The study strongly suggests that eating foods that have a lower energy density (for example, foods with more water and fewer calories, such as fruits and vegetables) can reduce how much one ends up eating over the course of the day -- no matter what time the food is eaten.