You have probably heard the saying, “You are what you eat.” But, have you ever heard of the phrase, “You are when you eat?” As well as the type of diet we consume, the timing of our meals can have a great impact on our overall health. Sister White has several quotes about the timing of meals that gives us an idea that adherence to a strict schedule is of vital importance. This month we will begin to delve into the science that supports the counsel given to us over 100 years ago.
Eating patterns have changed as our world has become busier, we hurry to our jobs and do not finish until late, we attend school and then we need to work on assignments. After work we run errands, we take care of our families; overall we have less time to prepare food, and we definitely no longer have time to sit down for what we refer to as “proper meals”.
Often people stay up late in the evenings, so they wake up from bed at the very last minute before having to rush out the door to get to work or school; they do not have time to eat so they skip breakfast. These same people often do not have time to prepare a meal for lunch either. They might buy a snack from a fast-food vendor or cafeteria and eat it whenever they have time. Then the biggest meal of the day is eaten when they arrive home in the evening. Often this meal does not satisfy the hunger from skipped or unsatisfactory meals during the day, so then hunger is satisfied by snacking before bedtime. Then there are others who do not have regular meal times, but just snack throughout the day whenever they have time. Others may have regular meals, but snack in between to satisfy their hunger. Do you fit in any of these scenarios in the timing of your meals and snacks schedule?
Our digestive system consists of many different parts, working together in harmony to break down the food that we eat into the various macronutrients, vitamins and minerals so that our body can absorb them and use them where needed. This includes things like providing energy, in building and repairing cells, for heart and lung function, and in keeping our immune system healthy. When we eat, the whole digestive tract initiates a process that takes several hours to complete, before food is absorbed into the body, and the waste products separated from the nutrients. We use anywhere from 15–30% of our calories that we consume to actually produce the energy to digest and use the food we eat. Whole foods require more calories to consume than processed foods. As an interesting aside, in a study comparing 100 calories of a whole food versus 100 calories of a processed food, the net calorie intake was 46% less for the whole food. For those who want to lose weight, eating the same amount of calories of whole foods vs processed foods will result in a greater weight loss.
The digestive process and the energy required is repeated every time we ingest even the smallest morsel of food or liquid. Therefore, those who eat continually throughout the day are using up the body’s energy for food digestion on an ongoing basis. This can contribute to a feeling of fatigue that so many people complain about. It may be more about the constant digestion of food versus lack of proper sleep. When the body has less energy, it decreases the body’s ability to digest food properly, and a vicious cycle is created.
When food enters our mouth and we take that first bite, the digestive process begins. Saliva, a digestive enzyme, combined with chewing, starts to break the food into smaller pieces. The food then enters the esophagus; once it reaches the end, a sphincter opens to allow the food to enter the stomach. In the stomach, digestive juices and the movement of stomach muscles break the food down even further. After the stomach has done its work, the thick liquid containing digestive juices and partially digested food moves into the small intestine. The small intestine further digests the food with help from the liver and pancreas. Finally, the walls of the small intestine absorb water and nutrients into the bloodstream. The waste products continue to move into the large intestine and are eliminated via the anus.
The length of time it takes for food to be fully digested and absorbed into the bloodstream can differ from the type of food eaten, one’s metabolism, body type, level of physical fitness and activity, sleep, water intake, gut health, age, and stress. Therefore, the length of the digestive process differs from person to person. However, there are some averages that we can look at.
Food generally stays in the stomach between 40–120 minutes or even longer. Once food leaves the stomach, it will spend another 40–120 minutes in the small intestine. The denser the food, i.e., the more protein or fat that it contains, the longer it takes to digest. Liquids leave the stomach the fastest as there is the least amount to digest. Plain water leaves the stomach in 10–20 minutes, whereas a smoothie can take up to 60 minutes.
Simple carbohydrate foods such as rice and pasta can average 30–60 minutes in the stomach. Vegetables take anywhere from 30–60 minutes to digest. Fruits, because they are simple sugars and contain fibre take 20–40 minutes to digest, depending on the type of fruit. Carbohydrates have the shortest digestion time because they are needed as fuel for the body, especially for the brain and working muscles, and can provide quick energy. Processed carbohydrates are absorbed faster than whole food carbohydrates because they do not contain fibre. Our body can store excess carbohydrates, thus the body has a ready supply of energy whenever needed.
Once protein and fats are added to the meal, the time in the stomach increases. Grains and beans take anywhere from 90 minutes to 3 hours to digest, whereas complete digestion of seeds and nuts takes 1–2 hours. Protein begins to be broken down in the stomach, however most of the protein is broken down into individual amino acids in the small intestine. Because proteins are not needed for energy, they are not in such immediate demand as carbohydrates, however proteins are used as building blocks for muscles, skin, hair and hormones and enzymes critical for healthy body function. Fats take the longest to digest, and are the last to leave the stomach. The majority of their digestive process takes place in the small intestine. Since fat and water do not mix, the processing time is slower because the end product of a fat needs to be water-soluble to enter the bloodstream.
The digestive process in those who eat animal products including meat, fish, dairy and eggs, take the longest because of the complexity of animal protein and saturated fats, along with preservatives and sodium. On average, three to four hours are needed to fully digest these products. Once the waste products of these foods move to the large intestine, it can take up to three days before they are eliminated. The length of time these foods remain in the large intestine is a major contributor to colon cancer.
Because we do not digest carbs, proteins, and fats in isolation, the digestion time for each meal can vary widely. On average, in a healthy person, the stomach can totally empty in 4–5 hours after a meal. Another two to three and a half hours are needed for food to be absorbed into the body via the small intestine. These numbers take into account people who consume meat as well as other foods. Another 30–40 hours is required for food to move through the large intestine before the waste is eliminated.
However, diets high in fiber, obtained solely in plant foods, speed up the digestive process and the movement of food through the digestive system. When comparing vegetarians to meat-eaters, the passage time for food is faster because vegetarians consume more fiber. For vegans who consume no animal products, their digestion time would be even quicker. They not only have faster digestive system transit times, they also have more frequent bowel movements. The less time that food sits in the large intestine, the healthier our digestive system will be. We should be consuming 25–30 grams of fiber daily. Any less will slow down transit times, especially when meat takes up a good portion of one’s diet. Meat-eaters also have delayed digestion because of the amount of fats consumed, especially saturated fats. They take more time and effort to be broken down when compared to protein and carbohydrates.
When all these factors are taken into account when we plan our meal times, what is the best pattern of eating? Sister White counsels us, “The stomach must have careful attention. It must not be kept in continual operation. Give this misused and much-abused organ some peace and quiet and rest…. After the regular meal is eaten, the stomach should be allowed to rest for five hours. Not a particle of food should be introduced into the stomach till the next meal. In this interval the stomach will perform its work and will then be in a condition to receive more food.” –Child Guidance, p. 389
Based on her counsel, and the evidence we have from science, we should space out our meals throughout the day so that we have at least five hours in between each meal in order for the digestive process to be fully completed before consuming more food. This gives the stomach time to rest, and improves our digestion and energy levels. Even eating the smallest morsel of food in between meals will start the digestive process all over again, and the stomach does not get its needed rest.
Next month we will learn more about the timing of meals and how it impacts our health.