Think of your body as a car, like a well-oiled machine. How well your car performs depends on the type of model the vehicle is but also the type of fuel it’s running on. The same is true for how our bodies run on energy from the foods we eat. Food is fuel. Everyone is completely different in how calories are used in the body for energy and how they are stored as fat. We could eat exactly the same foods as someone else and it would still be variable because we all absorb, store, and burn energy very differently. In this post I’ve outlined the three main factors that affect what percentage of food is absorbed through our gut, gets burned for energy, and how much is sent into fat cells for storage. Our genetics directly influence many of these factors, but also our environment and lifestyle choices greatly impact our fat-burning potential.
1. Your Gut Microbiome
Your gut is loaded with trillions of organisms, like bacteria and fungi, that are completely unique to you. We all have very different microbes lining our GI tract that are constantly replicating and dying. What we eat and our environmental interactions have a big influence on the type of organisms that can grow in our gut.
You need healthy bacteria in your gut for proper digestion of food and absorption of nutrients, as these microbes regulate appetite and have a major impact on your weight and overall health.
Recent studies of the gut microbiome show that thinner people have very different gut microbes compared to overweight individuals. This can absolutely affect our food absorption and hormonal signals that regulate weight gain. Healthy food creates a healthy gut. Feeding your gut organisms with nutritious foods helps the entire GI system perform better. We know (or should know!) that eating food that’s over-processed and loaded with sugar and chemicals can alter our microbiome in a negative way, leading to weight gain and eventually disease. A poor diet can increase inflammation not only in the gut but the entire body and may contribute to developing insulin resistance and related diseases like obesity and Type 2 Diabetes.
The gut is also home to most of our immune system. About 70% of our disease-fighting potential resides in the GI tract. Chronic stress, even mild stress of constant worry, activates the sympathetic nervous system creating a fight or flight response. Just thinking about something stressful can trigger the release of cortisol and a cascade of events that follow, including stress to the GI tract. Digestion is slowed as blood is diverted to muscles needed to either fight or run from a threat and the intestinal lining becomes inflamed and permeable, allowing toxins to pass through into the bloodstream.
The microbiome also regulates metabolism and mental health. Your brain and gut talk to each other all day through nerves and hormonal messengers known as The Gut-Brain Highway or Axis. What we eat can alter our levels of dopamine, serotonin, epinephrine, and norepinephrine in the brain, thus altering our entire mood. When these chemical neurotransmitters are out of balance chronically it can result in anxiety and depression, as well as sleep disorders, panic attacks, and irritable bowel changes.
What Can Damage Your Microbiome?
- Diet- processed foods, sugar & sugar substitutes, low fiber
- Eating the same foods/no variety
- Stress, especially chronic stress
- Tobacco and Alcohol use
- Sedentary lifestyle/no physical activity
- Poor sleep
- Certain medications, especially antibiotics
- Pollution from air/water and other toxins
- Chronic diseases, especially ones affecting the gut like Inflammatory Bowel Disease
2. Your Metabolism
Your metabolism, known as your basal metabolic rate (BMR), controls how fast or slow you burn food for energy. It’s your resting metabolism, meaning the energy required to keep your autonomic functions running, such as breathing, digesting food, and regulating body temperature. The hypothalamus in your brain regulates your metabolism based on your target set weight. It’s that number on the scale that you just can’t get under no matter what you do. That’s your target set weight, meant as a protective mechanism to maintain homeostasis so we don’t just burn through energy. This was great in ancient times when starvation was a real problem, but in modern America, we have an overabundance of food options available at any time of the day. Our diet and lifestyle choices can now override our target set weight and the scale continues to rise year after year.
When you are at a certain weight for a prolonged period of time it’s much harder to drop that set weight down, but not impossible! It must be done slowly. Losing weight at a fast pace will no doubt cause your metabolism to slow way down and regain the weight back. Once the hypothalamus gets the signal that you’ve dipped below its weight threshold, hormones are released into the bloodstream to slow the metabolism down, causing more calories to be stored as fat. Fatigue sets in, encouraging you to skip any physical activity and conserve energy, and food cravings increase. 96% of people who lose a drastic amount of weight in a short time gain it back (when done without gastric bypass surgery). When we lose weight, the fat cells shrink, not necessarily disappear. So the more adipose cells, or fat cells, that we make, the more cells we have that want to fill back up again with storage and weight gain.
The goal for sustained weight loss is to speed up your BMR over time while still maintaining a healthy intake of nutritious food that the body can use easily for energy. Not cutting calories, but changing the calories that you are eating. Feeding your body crappy food causes the GI tract to work overtime extracting little nutrition that it can find and tends to just store the rest in fat cells. Compared to healthy foods which can be easily converted to energy and are much smoother on the gut, which feeds back into the microbiome.
3. The Type of Calories You Eat
The type of food we eat has a major impact on our metabolism and gut health. Sugar and processed foods disrupt the microbiome and put stress on our digestive system. Certain foods release certain hormones acting as traffic control directing the body on what to do with calories, especially foods that contain hormones. The meat industry frequently uses antibiotics to control disease in animals, but also growth hormones to bulk up animal mass, and these hormones are passed onto us when we eat them. Extra growth hormones in humans build up fat mass. I suggest you look for antibiotic and hormone-free options when it comes to meat. Also grass-fed instead of grains, as grains are usually made of corn and also increase fat mass in the animal. In America, we use corn in nearly everything, especially high-fructose corn syrup. Not surprisingly, what is used to bulk up cattle is also bulking up humans.
Hormones signal us when we are hungry and also when we are full, as they regulate appetite. Ghrelin, a hormone from the stomach, signals the brain when you’re hungry. When we fill the stomach with food, Leptin, from the fat cells, signals the brain that storage is replenished and we can stop eating. The problem is that we overeat despite our feelings of fullness because that dessert just looks too good to pass up. We start to resist the satiation signals that Leptin is telling us. Over time we become used to eating more and more food, but the foods we over-consume are usually higher in calories, fat, and sugar, which alter our hormones and our gut microbiome. Another theory is that our hormonal signals are influenced by the hormones used in many animal and dairy products.
Foods high in sugars and starches also stimulate another hormone called insulin. Insulin is a growth hormone that pushes sugar from the bloodstream into cells. It’s a fat-storage hormone. So while insulin is high in the blood, you cannot burn fat. Insulin tells the body to store fat. The more sugar we eat, the more insulin tells us to store. Especially if we are not using that extra energy for physical activity.
So, what type of fuel are you putting in your tank? Are you eating foods that promote fat-burning or fat-storing? Here are some tips to restore a healthy gut and support your weight management goals.
Restore Your Gut Microbiome
- Eat a variety of nutritious foods high in fiber like fruits, vegetables, legumes, and whole grains. Fiber can be hard to break down in the GI tract, but with a variety of gut bacteria the fiber can be easily digested, so increase fiber consumption slowly
- Limit/Avoid processed foods that are low in fiber and high in sugar. This includes any foods that are prepackaged and have a long shelf life
- Avoid foods irritating to your gut
- Probiotics can help restore your healthy gut bacteria. Prebiotics can help feed existing organisms
- Avoid taking antibiotics if necessary. Taking antibiotics kills all bacteria, the good and bad, leaving your gut susceptible to overgrowth from bad organisms. So if you must take an antibiotic, take it with a probiotic
- Exercise regularly
- Avoid strict dieting. Diet trends that limit food variety, like Keto and Low-Carb, tend to also be low in whole grain and fiber intake which leads to an imbalanced gut and causes more weight gain later
- Manage your stress levels
- Improve sleep duration and quality
- Avoid smoking / regulate alcohol consumption
Focus on Healthy Calories
It’s not the number, it’s the type of calories that have a bigger influence on our fat regulation
- Avoid hidden sugars and choose to get your sweetness from natural sources like fruit and honey
- Eat lots of colors. Having a colorful plate means you’re getting lots of variety in your diet
- Healthy foods need prep. Avoid eating every meal from a box, as most of these are processed with added preservatives
- Learn your portions instead of counting every calorie
- Eat organic when you can, especially for meat. Grass-fed, antibiotic and hormone and steroid-free meat & dairy products may be a little more expensive, but it’s saving your health…. and chronic disease is a lot more expensive in the long run!
Disclaimer: The information in this article is designed for educational purposes only and is not intended to be a substitute for informed medical advice or care. This information should not be used to diagnose or treat any health conditions without consulting your healthcare provider. Information used is based on experience and opinion, not 100% evidence. Always consult with a health care practitioner before relying on any information in this article or on this website.