We used to believe that calories were all created equal. It sounded like common sense, seeing as one dietary calorie contains 4,284 Joules of energy. This naturally led us to believe that if you consume 2,000 calories a day and burn 2,000 calories a day, homeostasis on your body will be the result. Unfortunately, this isn’t the case—100 calories of gummy bears act very differently when consumed than 100 calories of asparagus—and adopting the blind calorie-counting method of eating is at least part of the reason we see more obesity as a society in recent decades. Here are a few examples that highlight HOW all calories aren’t created equal:
Fructose versus Glucose
Fructose and glucose are two simple sugars in many foods, and one gram of each gives you the same number of calories; however, your body metabolizes them very differently. Fructose is predominantly only be metabolized in the liver, where as glucose gets metabolized by all the tissues in the body. On top of this, fructose leads to higher levels of the hormone Ghrelin (known as the hunger hormone). So, consuming more fructose means you’ll probably feel more hunger than satiation. (). In case that’s not enough reason to steer clear of fructose—and, of course, high-fructose corn syrup—it has also been shown to lead to insulin resistance and an increase in fat around your mid-section. But wait, isn’t there fructose in fruit? There is, but fruit are also rich in fiber and water, which prevents much of the negative damage. The long and the short of it is fructose calories do more hormonal and metabolic damage on your health than glucose.
Protein’s Metabolic Advantage
Different foods go through different metabolic pathways in your body, some of which are more effective than others. For example, protein has four calories per gram, but much of these calories are lost as heat when your body metabolizes them (what is known as the thermic effect). In other words, it requires much more energy to metabolize protein than it does to metabolize fat and carbs.
Thermic Effect Percentages:
• Protein: 25-30%
• Carbs: 6-8 %
• Fat: 2-3 %
Based on the above percentages, this means if you consume 100 calories of protein, you end up with only 75 calories in your body, because of the 25% thermic effect (meaning 25% of protein’s calories get lost as heat). On the other hand, if you eat 100 grams of carbs, your body will still end up with 94 calories, because you only lose around 6 calories as heat due to the thermic effect. (). It’s no surprise then that various studies have shown that a higher protein diet boosts your metabolism as compared to a lower protein diet.
Protein and Portion Control
On top of its metabolic effect, protein also has a special appetite-killing power, so to speak. Protein calories are the most effective at making you feel full. You have probably noticed this. You can eat waffle after waffle loaded with berries, but you’re likely not going to eat three steaks for dinner. This study () showed that people who eat more protein (30 percent of their diet was protein) ate 441 fewer calories per day and lost 11 lb. on average in 12 weeks. This essentially comes down to the satiety index. I already pointed out how your body feels like a bottomless pit when you’re throwing back waffles, or ice cream, but you’ll have a hard time getting the same amount of calories of milk, eggs or meat into your system.
The glycemic index basically has to do with measuring how fast foods raise your blood sugar. As expected, highly refined carbohydrates spike your blood sugar faster than protein and healthy fats, for example. Blood sugar spikes lead to blood sugar crashes, which lead to cravings for more high-carb foods. In short, eating more foods higher on the glycemic index means you’re putting yourself more at risk of both gaining weight and getting Type 2 diabetes.
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