Whenever someone comes to me for advice on how to lose weight, the first thing I do is explain to them how their body processes sugar. By sugar I don't just mean table sugar, I mean any type of carbohydrate. Simple carbohydrates like table sugar, white flour, and high fructose corn syrup are processed quickly in the body, while complex carbs like starches and whole grains are broken down more slowly. They are an important part of our diets, but the USDA's suggestion that they should make up the bulk of our diets has led many down the path to obesity. I don't tell people to give up all carbs and stick only to a low carb diet (although I am a big fan of that particular diet), I just find that with a little bit of info on how their body processes sugar, people finally understand how to shape their own diets for success.
How does sugar make you fat?
Sugar itself cannot be stored very well, so your body tries to use it to fuel your muscles and cells immediately. This and the fact that the brain and nervous system relies on sugar for fuel instead of fat is the reason people mistakenly concluded that carbohydrates are your body's preferred fuel. The reality is that your brain can create the fuel it needs from fat (called ketones), and reason sugar is used first is because it is difficult to store. Think of sugar like fresh produce and fat like canned goods. Since the produce isn't going to last as long as the canned goods, your body grabs the produce (sugar) first and stores all the canned goods (fat) for later.
It does this by releasing a storage hormone called insulin. Insulin tells your cells to grab all the sugar out of the bloodstream for fuel and it tells your fat cells to store any fat floating around in the bloodstream for a few hours. This is really how sugar makes you gain weight so badly. While some sugar is converted into fat in the liver, the majority comes from the fat you consume while your body is in insulin-induced storage mode.
You just finished eating, but you'll want more soon
Added sugars tend to spike your insulin so you quickly go into storage mode. Another problem with a sudden spike in insulin is that the signal for your body to stop producing insulin often comes too late. This causes your blood sugar levels to drop too low for a while which in turn sends your appetite soaring as you look for sugary foods to bring your levels back up. Foods with lots of easily processed simple sugars (like soda, juice, white bread, pasta, white rice, sugary cereals) jumpstart this insulin roller coaster and can really bring on the munchies. One of the benefits of complex carbohydrates is that they are digested more slowly so they don't trigger this roller coaster.
Combine a super charged appetite with your body locked into fat storage mode, and it's easy to see how too much sugar can easily cause big problems.
But wait, it gets worse
As you eat more and more sugar and your body becomes flooded with insulin, your cells become less sensitive to this storage hormone. Your body then starts to manufacture more and more insulin to get the sugar out of your system before it can do harm. This is when weight starts spiraling out of control. More insulin means your fat cells will store more fat and not release it, making it harder to lose weight and much easier to gain it.
Is added sugar a toxic substance?
New research from the journal JAMA Internal Medicine shows that if you get more than 25% of your daily calories from foods and drinks containing added sugar, you have triple the risk of dying from heart disease. Even moderate intake (10% to 25%) increases cardiovascular risk by 30%. This means that even one sugar-sweetened drink a day is enough to increase the risk of dying from cardiovascular disease. Sugar not only makes you fat, but more and more, researchers are starting to realize that sugar is the source of inflammation that negatively impacts your health.
Why is added sugar so unhealthy?
To understand why added sugar causes inflammation in the average person, you need to understand how sugar harms people with diabetes. When your blood sugar is high, a small percentage of glucose bonds with the hemoglobin in your red blood cells. Since blood cells are turned over every 3 months, consistently high blood sugar can cause this layer of sugar to thicken to harmful levels. To test how well diabetics have controlled their blood sugar over the past 3 months, doctors measure how thick this layer of sugar is on their blood cells. When the layer is thin they’re fine, when it’s thick their blood cells become coated in a rough layer of sugar that effectively turns their blood cells into little chunks of sandpaper endlessly scrubbing their blood vessels. That’s why diabetes is so harmful. As the tiny vessels in the body are destroyed, diabetics eventually start losing organs and limbs. While this level of destruction is not a concern for the average person, maintaining high levels of blood sugar can irritate your blood vessels, cause damage over time, and set you up for serious health issues later in life.
So what should you do?
You don't have to throw out all sugar, you just need to ease back on the foods that give you the most problems. Everyone has heard stories of people losing tons of weight by simply giving up soda. That's because soda (as well as juices, sports drinks, and alcoholic beverages) makes you store fat for hours afterwards while simultaneously making you crave unhealthy foods. That's a dangerous combo.
You don't need to avoid carbohydrates entirely but you should reduce the simple sugars and focus on more complex carbohydrates that are higher on the glycemic index (GI). The glycemic index ranks carbohydrates on a scale from 0 to 100 according to the extent to which they raise blood sugar levels after eating. Foods with a high GI are rapidly digested and absorbed, so they are the ones that will put you on the carb roller coaster I spoke of earlier. Low-GI foods, however, are absorbed slowly so they gradually raise blood sugar and insulin levels. Low GI foods benefit weight control because they help control appetite and keep you satisfied longer. They've also been shown to improve both glucose and lipid levels in people with diabetes (type 1 and type 2). You can check where foods fall on the glycemic index here.
Added simple sugars in processed foods are what really impact your health, and the most important thing to reduce in your diet. According to the World Health Organization, you should limit the amount of added sugar you eat to about 10% of your total daily calories. Naturally occurring sugars like those found in fruit are fine, but try to limit foods like sugary cereals, candy, dairy deserts, bread, and sugary drinks. These foods are really meant to be treats, but they've become a standard part of every meal. Moving them back to treats will get the amount of sugar in your diet back down to reasonable levels without making you feel deprived. Trying to go cold turkey in our society is likely just going to lead to frustration and then eventual binging when you give up on the whole idea. Keep it reasonable and adjust the rest of your meals to deal with hormonal effects of carbohydrates.
1. Add protein and avoid fat with your sugars: Protein fills you up without packing on the pounds. Your body is going to store the fat you eat when your insulin is up, so when it is, enjoy some nice lean protein so your meals are filling instead of fattening.
2. Fruit and vegetables are free: Even though fruit is sweet, it barely raises insulin levels. Fructose is handled differently in your body. It is metabolized in the liver instead of triggering a release of insulin. You can eat as much fruit and vegetables as you want. Don't even bother counting the calories because they don't matter. Your body knows how to handle fruit and send back signals to keep you from overdoing it. If you're going to have something sweet, this is another good way to fill up on something healthy so you don't pack on the pounds.
If you understand how your body works, you can make simple adjustments that make a big difference. You don't have to deprive yourself of your favorite treats, just limit them so they become treats and beware the affects they have on your appetite.