Eating earlier may curb some cravings
Dear Doctors: I heard on the news about a study that says you won’t get as hungry if you eat all of your meals earlier in the day. Does that have to do with the way the body clock works? It seems like circadian rhythms affect everything we do. Can you talk about that, and about this study?
Dear Reader: Your question returns us to the fascinating field of chronobiology. As the word suggests, it’s the study of biological rhythms in relation to the daily cycle of light and dark. While written references to the existence of a “biological clock” date back many centuries, the first known scientific observations on the phenomenon were made in the early 1700s. The modern branch of this science traces its roots to the 1950s, with fruit fly experiments and a few sleep studies. Today, chronobiology is a robust area of research.
What was once known as the body clock has been fine-tuned into the circadian cycle. With hundreds of academic studies in the last few decades, we have learned that the daily 24-hour cycle of light and dark not only influences virtually every biological function, but it also appears to be built into our bodies at the cellular level. Several recent studies have looked into the effects of our bodies’ circadian rhythms on diet and exercise. The latter generated some interesting results, which we’ll write about soon.
The research that you are asking about, which recently appeared in the journal Cell Metabolism, focused on diet. Specifically, the researchers wondered if the time of day at which we eat our meals is important. Sixteen adults who were either overweight or obese were randomly divided into two groups. One group ate their meals at 8 a.m., noon and 4 p.m.; the other group ate at noon, 4 p.m. and 8 p.m. Each participant was served the same caloriecontrolled diet, which was provided by the researchers. Information about each person’s level of hunger and satiety was collected 18 times per day. Blood tests and tests for body fat percentage, energy expenditure and body temperature were done on three different days. This part of the study lasted seven days. After a break of two weeks, during which all of the participants again ate the same diet, they switched roles: The “early” group time shifted to eating the controlled diet four hours later, and the “late” group was served their trio of meals four hours earlier.
Once the lab tests and daily self-reports were analyzed, it turned out that the early eaters felt half as hungry throughout the day as the later eaters. They also burned more calories than the other group did. Those who ate later in the day reported increased cravings for starchy and salty foods. Blood tests revealed that those who ate later in the day had levels of leptin, a hormone that causes hunger, that were 33% higher than in the early eating group. As with all studies, particularly those that are small and brief, further investigation is needed. But the results are certainly intriguing.
CHILDREN’S MILD DIARRHEA IS EXPECTED, CAN BE TREATED AT HOME
Dear Doctors: After our 4-year-old daughter started day care, she had a few episodes of diarrhea. It lasted only a day or two each time, but it’s not something that happened while we were home during the pandemic. What causes it? Is it dangerous? What’s the best way to treat it?
Dear Reader: Although it can be alarming for the parent and scary and uncomfortable for the child, diarrhea is a common problem in younger children. This is particularly true for those under the age of 5.
Most diarrhea in children in the United States is caused by gastrointestinal viruses, which can occur in group situations such as day care. They are often transmitted due to lapses in personal hygiene. Considering how young children interact with the world through the sense of touch and how often their fingers wind up in their mouths, their being susceptible to viral diarrhea isn’t that surprising. Additional causes can be bacterial infection, food allergies or intolerance, parasitic infection or a reaction to a medication, vitamin or supplement.
Symptoms include passing loose or watery stools several times a day, often accompanied by cramping or bloating. Some children feel nauseated, experience vomiting and develop a fever.
Your question refers to what is known as acute diarrhea. This lasts anywhere from a day or two to up to three weeks. Diarrhea that continues beyond three weeks is known as chronic and may be an indicator of a more serious problem. Chronic diarrhea can be a symptom of a disease or of a functional disorder in which the bowel is not working as it should.
Any time severe or ongoing diarrhea occurs — or when it is accompanied by a fever of 102 degrees or higher, severe abdominal or rectal pain, stools that contain blood or that appear black and tarry — it’s important to seek medical care.
All forms of diarrhea should be taken seriously. That’s because, even in the short term, the loss of fluids that occurs during diarrhea can lead to dehydration. With a young child’s small size, this can happen quickly. Symptoms
of dehydration include an increase in thirst, a dry mouth, a lack of energy and a decrease in both the frequency of urination and the output of urine. For infants, this may mean they have gone three or more hours without wetting a diaper.
When someone becomes dehydrated, the loss of fluid in the body becomes evident in the elasticity of their skin. That is, when the skin is pinched and released, it fails to immediately rebound to its original shape. This is known as a decrease in turgor and is a symptom of dehydration.
A child with the mild form of diarrhea that you have described can safely be treated at home. This includes encouraging them to rest, to drink fluids throughout the day and to follow a healthy diet. Medications to slow bowel movements are available, but check with your doctor before using them. When diarrhea is accompanied by vomiting, oral rehydration solutions are recommended. It’s important for the child and their caregivers to wash their hands, particularly after using or helping with the bathroom.
EATING A VARIED DIET WILL HELP WITH GETTING COMPLETE PROTEINS
Dear Doctors: What does it mean when something is a “complete protein”? A friend said that when I count beans or grains as a protein, it’s not the same nutritional value as meat or cheese. Are there really different kinds of protein? Is he right that it matters which kind of protein you eat?
Dear Reader: Proteins are vital to the health and function of our bodies. That makes it important to understand what they are and how they fit into the diet.
Dietary protein, along with carbohydrates and fats, is what is known as a macronutrient. These are nutrients the body requires in large quantities to maintain health
and function. Macronutrients have unique properties that distinguish them from one another, and they are all used by the body as sources of energy.
When it comes to proteins, they are found in every cell in the human body. They are used for cell structure, growth and repair, and they play a central role in numerous metabolic processes. The antibodies that defend the body are made up of proteins, as are the enzymes that carry out virtually every chemical reaction within the cells. Small wonder, then, that proteins are often referred to as the building blocks of life.
You are correct that beans and grains are among a wide range of plant-based proteins. But your friend is also accurate in saying many of these proteins are incomplete. To explain, we need to dip a toe into biochemistry. Proteins are made up of long chains of molecules called amino acids. In carrying out the countless functions that maintain life, our bodies use 20 different amino acids. These are joined together in varying lengths and
combinations to make thousands of different types of proteins, each with a unique job.
Although our bodies produce some of the amino acids we need, it can’t make them all. The nine it can’t make are known as essential amino acids, and they must be obtained through diet. They are histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine. Foods such as meat, fish, poultry, eggs and dairy products contain all of the amino acids that the body needs. They are also present in the exact proportions required for optimal health and body functions. That makes them “complete” proteins.
Other than soy, quinoa and buckwheat, which are complete proteins in themselves, most plantbased proteins are either low in certain amino acids or are missing them altogether. That makes them “incomplete” proteins. The good news is that by eating a variety of plant-based proteins, you can provide your body with combinations of amino acids that add up to a complete protein.
For instance, beans and rice each lack certain essential amino acids and are thus incomplete proteins. But eaten together, they form a complete protein, because each contributes the amino acids the other is missing.
While this concept of combining plant-based proteins is particularly important for those on a meat-free diet, it applies to all of us. By eating from a wide range of foods, including vegetables, grains, rice, nuts, seeds and legumes, you’ll get the protein your body needs.
Eve Glazier, M.D., MBA, is an internist and associate professor of medicine at UCLA Health. Elizabeth Ko, M.D., is an internist and assistant professor of medicine at UCLA Health. Send your questions to askthedoctors@ mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10960 Wilshire Blvd., Suite 1955, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.