by LCR Health Staff Writer
There is a big difference between metabolism and digestion. Some people think that they can’t lose weight because they have a slow metabolism. Others think that if they have fast digestion, it means that they must have a fast metabolism. As it turns out, the old adage of “eat less and exercise more” may not always be the best strategy for preventing long-term weight gain.1
Are you dealing with a messed-up metabolism? It may be more common than you might imagine. Here, you will learn about metabolic rate, how it is affected by eating less, and what you can do to support healthy weight loss.
Some Basics on The Human Digestive System and Metabolic Rate
Human Digestive System
Digestion is the process of breaking down food, so our bodies are able to separate what is going to be used, and what is going to go to waste. This is the first part of what happens when we ingest food.
The human digestive system works by breaking down food into smaller pieces so that the nutrients contained within the food can be absorbed into the bloodstream. Digestion is a mechanical and chemical process.2
Metabolism is the process by which our cells convert the food we eat into the energy we need to keep our bodies functioning.3,4
This is the second part of what happens when we ingest food. It encompasses chemical and physical processes such as:
- Blood circulation
- Body temperature control
- Muscle contraction
- Digestion of food and nutrients
- Waste elimination
- Brain and nerve functioning5
Metabolism measures the amount of oxygen used by the body over a specific amount of time.6
There are two parts to how our metabolism functions and they should ideally be in balance:
Catabolism is the process that breaks down macronutrients (carbohydrates, proteins, and dietary fats) into molecules that can be used to provide the body with energy.
Anabolism is the process of rebuilding and repairing the body. Any excess nutrients not used during this process become stored as fat.7
Your body’s total energy expenditure is known as the metabolic rate. Even at rest, your body needs to keep certain systems supplied with energy, such as breathing, ensuring that the heartbeats, providing resources for cells to be repaired, and adjusting hormone levels.
Your body burns calories in three distinct ways:
- Via the mechanism of the basal metabolic rate
- As a result of everyday activities
- As a result of exercise8
The measurement, known as the basal metabolic rate (BMR), is made when the body is at rest. It measures the amount of energy your body needs to maintain homeostasis.9 Basal metabolism can be influenced by your body’s level of nutritional health, overall health status, and body temperature, among other factors.10
A number of factors affect metabolism. They are food, exercise, current weight, former weight, and deprivation of food and sleep.
How Does the Food You Eat Affect Metabolism?
Does eating specific foods make your metabolism faster? Would that make your body lose weight and achieve fat loss? What about only eating at certain times of the day? These are common questions that come up. Fortunately, your metabolism does not vary much throughout the day, regardless of what you eat or when you eat it. But there are a handful of instances in which you can help speed up your metabolism. For example, caffeine speeds up the rate at which your body burns calories, but the effect only lasts for a short time then goes back to its regular rate.11
For weight loss, foods to avoid include products with empty carbs such as cakes, cookies, candy bars, potato chips, and soft drinks, as well as those that contain refined white flour, like bread. Unfortunately, the body stores these foods as fat. Instead, if you want to achieve fat loss, consume foods rich in whole grains, lean proteins, vegetables, and fruit. These are foods whose energy can be more available for immediate use. The important part about metabolism is to not focus on the metabolic rate – but on the quality of the metabolic process.12
How Does Your Current Weight Affect Metabolism?
Your weight is largely dependent on the presence and proper functioning of hormones such as insulin. The release of insulin after a meal acts as the trigger for anabolism. But if you are overweight, it is possible that your body will no longer respond well to insulin. Therefore, sugar may remain in your blood rather than being stored as energy.13 This will result in weight gain rather than fat loss.
How Does Body Fat Affect Metabolism?
There are two types of fat in the body. “White fat” is the result of your body storing excess calories. It is often considered “bad fat.” Weight gain occurs when your body accumulates too much white fat. “Brown fat” is considered “good fat.” Its primary function is to turn food into body heat by breaking down sugar and fat molecules. Brown fat is activated by cold temperatures. This leads to a slew of metabolic changes in the body.14,15
Different Dieting Methods: Can They Lead To A Messed Up Metabolism?
Calorie Restriction and Intermittent Fasting
When it comes to dieting, there are two ways to restrict calories – and they have very different outcomes. The first is continuous calorie restriction, which is a diet that consists of a significant reduction of calories that are consumed. The other is intermittent calorie restriction. Also known as intermittent fasting, this consists of going for extended periods of time without eating.
Eating a restricted-calorie diet can cause metabolic problems by triggering increased hunger and additional eating. This may result in weight being regained. It may also affect hormone levels and contribute to age-related muscle wasting.16
On the other hand, intermittent fasting can be an effective dieting solution for short-term weight loss, among people of varying weights, from normal to overweight and obese. It may also be helpful in stabilizing blood sugar.17,18
Starvation mode is the biological process of restricting calories to the point that bodyweight declines. Rather than burning calories, the body grabs onto any calories it can get. As a result, a person may gain weight rather than losing it.19
How do you avoid this type of metabolic starvation?
A normal metabolic process consists of hormones, neurotransmitters, proteins, and a host of chemical messengers. Their role is to regulate the number of calories that get burned through actions such as walking, breathing, talking, and exercising. However, when a person heavily restricts calories, the body goes into overdrive to retain enough calories required to have the energy to function properly.20 You can avoid this outcome by eating lots of lean protein (25-30g per meal) to preserve and rebuild muscles, manage body weight, and keep cardiometabolic risk factors in check.21
Occasionally, metabolism may be affected by an eating disorder. One disorder distorts the perception of weight, resulting in extreme weight control behaviours and starvation. When the metabolism is dysregulated and set too low, the body does not want to gain weight.22
Binge eating followed by purging is another eating disorder that wreaks havoc on body weight and affects metabolism.23 This cycle disrupts sodium, potassium, chloride, and other electrolyte levels, and affects pH levels as well as many other metabolic complications and related illnesses.24
Healthy Ways to Support A Healthy Metabolism
How Does Exercise Affect Metabolism?
Your resting metabolism accounts for most of the calories that you burn during the day. Exercising is one of the few ways that you can influence your metabolic rate. This is because muscle tissue is metabolically more active and burns more calories than fat tissue. A bonus outcome is that once you build more muscle tissue, your body still burns more calories – even when you are sitting still.25
A big factor that determines your metabolism is genetics. Your genes play the biggest part in the rate of your metabolism, and the speed is not related to your body size or composition. Age also plays a role. Having a slower metabolism means that fewer calories are burned, which affects the ability to lose weight. People who have a slower metabolism store more fat in the body. Conversely, people with faster metabolism can burn calories at a faster pace. That is why two people with similar weights can eat the same amount of food, but one of them gains weight while the other one doesn’t.26
Another factor is muscle tissue. Your body’s ability to burn calories is dependent upon the amount of muscle tissue that you have. This varies by gender (women tend to have less muscle than men) and by age (older people tend to have less muscle tissue than younger people). While building muscle mass can boost metabolism, the best way to burn more calories is to move a lot: running, walking, and playing sports.27
Eating more protein is also a contributing factor in altering the speed of metabolism. This process, known as the thermic effect, happens when we eat, digest, and store food. The thermic effect of protein is higher than carbs and fats, so it takes longer for the body to absorb it. To speed up your metabolism, you could combine more protein intake with lifting weights.28
How Do Proper Eating and Sleeping Affect Metabolism?
Reducing calorie intake by eating too little can cause your body to burn calories more slowly. As an example, skipping meals such as breakfast can confuse your body into thinking that there is a shortage of food. In that case, the body tries to preserve all the calories it can find, which lowers the metabolic burn rate.29
To avoid a messed-up metabolic situation, it is best to follow a dieting routine of eating several small meals a day. This should include vegetables, whole grains, and lean proteins.
It is also vital to get enough sleep. Both lack of sleep and sleep disorders significantly impact metabolic homeostasis in a negative way. This can lead to high insulin levels, insulin resistance, and more fat storage, leading to weight gain. Studies have shown that 6-8 hours of sleep is best for optimal metabolic performance.30
Approach Weight Loss “In Spite Of” Your Metabolism Instead of Trying To “Beat It”
The most reliable ways to lose weight and avoid dysregulated metabolism are to stay active and to eat a healthy diet. Your body thrives when its metabolism is at its peak. This occurs when you maintain consistent routines, exercise and build muscle, get good and adequate sleep, and eat good quality sources of calories. Avoid situations where you starve your body of calories and nutrition over an extended period of time. Consult your doctor for a weight loss plan tailored to your specific situation.