How Sugar Kills Your Metabolism
Sugar!! It’s so delicious, right?
We’re hard-wired to crave sugar. That’s because as we humans evolved over thousands of years we typically lived in food deserts, meaning that we went through long periods of time where we didn’t have a lot of food around. Sugar is made up of glucose, which our brain and body need to survive. So to survive, our brains became wired to crave sugar: sugary things provide the easiest and simplest fuel around, which equals survival.
The whole point of eating is, very basically, to keep us alive. If our blood glucose level (a.k.a blood sugar level) drops too low we can die, and quickly, because our brain basically goes into starvation mode. And for most of us, we don’t have to worry too much about our blood sugar levels dipping so dangerously low because our bodies have adapted ways to make “brain food” in times of famine. An important exception here is people living with type I diabetes mellitus, who must constantly monitor their blood sugar levels very carefully.
OK, so our ancestors evolved in food deserts, meaning that their bodies got really good at raising blood glucose levels to survive. Fast forward to today: most of us in the first world are surrounded by food, and SO MUCH of it is processed with added sugars.
We have the opposite problem our ancestors faced: now we should be worried about eating too much sugar, not about needing enough glucose to survive.
Our bodies do need glucose to survive, but not that much. A healthy blood glucose level (a.k.a blood sugar level) should be about 60-99 in fasting states (we’re in a fasting state when we haven’t eaten in at least 8 hours; for example, most of us are in a fasting state when we wake up in the morning. Hence, “break-fast”). Diabetes typically starts at fasting blood sugar levels of 126.
Our bodies can also make blood glucose from other foods like grains, proteins, even veggies (and of course fruits, which have natural sugars in them). Our bodies can process between 20-30 grams of table sugar or added sugar a day (this includes any added sugars in foods: check your nutrition facts to see how many grams of sugar are in one serving of your favorite food!).
HOW ARE SUGAR AND METABOLISM RELATED?
Your body’s metabolism is a process that literally goes on inside every single one of the trillions of cells that make up YOU. So there’s no one location that we can point to on your body and say “the problem is here” when we’re trying to understand what’s going on with your metabolism.
What we need instead is to understand what we’re talking about when we talk about your metabolism.
Metabolism is how we make energy; more specifically, it’s the process of creating the vital energy that we need to survive. We make this energy from the calories that we eat and drink.
Food has energy that we can access, and it’s measured in calories. Sugar is a pretty high-calorie food, so it has a lot of energy in it for our bodies to process.
This energy from food becomes energy for our bodies inside the mitochondria of every single one of our trillions of cells. The mitochondria are little “energy factories” that are inside every single cell. They are responsiblefor setting our metabolic rate: the faster the mitochondria work, the faster our metabolism will be. Some cells have more “energy factories” or mitochondria than others: our muscle cells (especially our heart muscle) and our brain have the most, because these are the parts of us that need the most energy to survive.
So the energy from the food we eat eventually makes it to the mitochondria, or our “energy factories,” which then turn food energy into energy our bodies can use to move, breathe, laugh, etc.
When you eat a lot of sugar (a high-calorie food), you are asking your mitochondria to make a lot of energy for your body, fast.
WANT MORE SCIENCE ON THIS? HEAD TO THE BOTTOM OF THE ARTICLE FOR MORE!*
SO HOW DOES EATING TOO MUCH SUGAR SLOW MY METABOLISM?
When you eat too much sugar, you’re asking your mitochondria to process much more energy than they can safely process. This causes a lot of things to happen, which all combine to slow down your metabolism. A high-sugar diet
causes an acidic environment inside the mitochondria and in the cell, which makes the mitochondria sluggish —> your metabolism slows down
It depletes vitamins that your mitochondria need to make energy
It causes cell damage by making lots of free radicals. These guys are responsible for early aging.
causes rapid weight gain: after a high-sugar meal, our cells might fill up with all of the glucose they can fit (which is often too much). This may also leave a lot of blood sugar in the bloodstream, which we know is dangerous. In this case, blood sugar is then scooped out of the bloodstream and converted to fat, where it’s stored in our fat cells. So even if you’re eating a low-fat diet, if you’re eating a lot of sugar and simple carbs, you’ll still gain fat.
DID YOU KNOW THAT ADDED SUGAR HIDES ALL OVER THE PLACE?
It’s true. If you get nothing else from this whole article, please take this away: READ YOUR FOOD LABELS. Sugar sneaks into foods all the time, and it has a lot of sneaky names that you may not recognize. However, the FDA requires that all packaged and processed foods be labeled with nutrition information, so read your food labels to find out the amount of sugar in a serving of food. (Note that a serving may be smaller than you think!)
Why would companies add sugar to foods that don’t seem sweet, like frozen pizza, ketchup, salad dressing etc.? Added sugar is ubiquitous in processed and packaged foods. It makes things taste better (remember how I said above,that we’re hard-wired to crave sugar? It’s true, and companies that process and package your food know this!). It makes you crave them. It makes you think about them when they’re not around, and you may even find yourself driving to the store for no reason other than to buy them.
SO HOW CAN YOU BOOST YOUR METABOLISM?
Read your food labels!! How much sugar is there in your favorite foods?
Aim to eat no more than 20-30 grams of sugar a day, if you do eat sugar. To best support your metabolism, go sugar free. FYI: when speaking about going sugar free, I do not include the sugar that is naturally found in fruit. Fruit in moderation is an amazing and very healthy part of a plant based diet because it’s full of fiber, vitamins, minerals, and antioxidants. I encourage you to begin to think of fruit as your dessert.
Break your sugar addiction: stop eating all sugar for a week; the next time you eat sugary food, you’ll be shocked at how sweet it tastes!
Go for “whole foods desserts”: enjoy fresh fruit like pineapple, mango, apple, banana, etc. for dessert.
Try sugar free sweeteners: to be clear, I am NOT talking about artificial sweeteners. I never recommend that people use aspartame, Splenda, Equal, Nutrasweet, or anything like that. In fact, I tell them to avoid it. Instead, try stevia for a calorie-free plant-based sweetener that is good for you.
When you do eat sugary food, make sure you're also getting some dietary fiber, which slows down the absorption of sugar so that your body can handle it better. Also, do something active after eating sugar like going for a walk.
If you’re looking to boost your metabolism, cutting out sugar may be exactly what you need. My patients are often shocked at how much better they feel after just a week away from sugar: you may be pleasantly surprised too! Challenge yourself to explore your relationship with sugar by cutting it out of your diet for one week. Your mitochondria will thank you.
*THE SCIENCE: METABOLISM AND BLOOD SUGAR
Here’s the process, in a nutshell: the food we eat is broken down in our digestive system, starting with chewing. Once it’s small enough, our food is absorbed through the digestive tract into the bloodstream. Sugar is really small, so it’s absorbed really quickly. Proteins, complex carbs, and fats are all bigger, so they are absorbed more slowly because they have to be broken down first.
So: when we eat or drink a lot of sugar, we’re also dumping a lot of sugar into our bloodstream really quickly, causing a blood sugar spike. Too much blood sugar at once is actually dangerous because it can cause a lot of cell damage, so to remedy this our bodies will actually move the sugar (as glucose) out of our bloodstream and into our cells (insulin is the hormone that actually moves blood sugar into our cells).
This is how the food we eat eventually gets into our cells: when our blood sugar levels rise, insulin is produced and released into the bloodstream —> insulin “opens the doors” to our cells —> blood sugar (as glucose) can move into our cells.
Once inside the cells, it moves to our mitochondria where it’s transformed into energy.
The vital energy we need to survive is made inside the mitochondria in two parts:
the Krebs cycle (is anyone remembering high school biology and cringing?)
the electron transport chain (anyone?…)
When you dump a bunch of sugar into your cells all at once, the mitochondria get overwhelmed as these processes speed up. The net effect is depletion of the vitamins and minerals needed to run these processes as well as the formation of lots of free radicals, which damage our cells and cause early cellular aging. It also makes the mitochondria work less efficiently which results in a slowing down of our metabolic rate.
A high sugar intake also promotes weight gain as excess sugar as energy is stored as fat. Fat is like a sponge, soaking up toxins in our body. The presence of these toxins as they’re stored inside our cells also promote cellular damage and early cellular aging. Giving your body a chance to detox these toxins, and to reset your metabolic function, is a great way to jump-start a weight loss and health promoting program.