Why Do I Gain and Lose Weight So Easily?

You wake up one morning, and decide to log some serious weight loss wins on your Fitbit. After all, it tracks your steps, lets you know how many calories you’re consuming, and motivates you to keep going. For the first time in a long time, you’re feeling motivated. You’ve got a lot to lose: about 40 pounds, to be exact. But as soon as you hit that magic number, something weird happens. You start gaining weight, rather quickly. You double down on your Fitbit, determined to uncover the root cause of this unexpected weight gain. You research, you try new tricks, and nothing seems to work. After several weeks, you’re at your wit’s end, weighing more than you’ve ever weighed in your life. Will this ever end?

Here’s the catch: you’re not alone. We’ll call you Lisa, and you’re a 35-year-old insurance broker who finds herself in a bit of a slump. Lisa recently lost 40 pounds, which transformed her whole life. Now that she’s at a healthy weight, she’s feeling great. She wants to keep up her fitness regimen, and has her eye on a pair of Levi’s that she spotted in a fashion magazine. One would think that after losing such a substantial amount of weight, that Lisa would be able to keep it off. But as we’ve established, you’re not alone. Here’s the problem: after hitting a metabolic peak following her weight loss, Lisa found that keeping the weight off was more challenging than losing it in the first place. And that’s not hyperbole; it’s literally true. After she reached her target weight, Lisa discovered that she was gaining weight even when she ate healthy foods and exercised regularly. She’d wake up one morning, and would discover that she’d somehow put on a pound or two during the night. So here’s the question: how does losing weight make you gain more weight? And is there a way for you, as a newly minted fitness enthusiast, to keep off the pounds and live a healthy lifestyle? Let’s explore.

The Metabolism Advantage

When you lose weight, your body’s physiology changes. It’s now easier for you to stay at a healthy weight, and you have an advantage when it comes to keeping off the pounds. Here’s an overview of what happens when you lose weight:

  • Your body’s metabolism changes. It learns to burn calories more efficiently.
  • Your body’s hormonal profile changes. Your levels of cortisol (the ‘stress’ hormone’) lower, and you become more efficient at producing leptin (the ‘satiety’ hormone’). Leptin allows you to feel full even after a small meal, and aids in the regulation of appetite. If you’re still hungry, leptin helps stimulate the appetite center in your brain, which results in you eating something higher in calories.
  • Your body’s temperature drops. The lower your body temperature, the more you’re able to cut calories. Studies show that weight loss can increase your body temperature by up to a whopping 4°F (2°C). It’s likely that this is the reason why you begin to see weight loss as a cold winter morning rather than a glorious summer morning. As your body temperature lowers, your body is better able to stay active, and it’s easier for it to use fats as an energy source. Your body also produces more free radicals, which are small molecules that damage cells, when your body is cold. The lower your body temperature, the more you need to protect yourself from cell damage, and thus, you gain more weight.
  • More hormones are produced. When you lose weight, your body produces more of the ‘fight or flight’ hormones. These hormones help you to be more active, alert, and responsive to changes in your environment. In a nutshell, these are the hormones that make you feel excited, empowered, and alive!
  • Less water is required. As you lose weight, your body needs less water to stay hydrated. Less frequent urination reduces the demand for water, as does exercise in the sun. Your body becomes more efficient at eliminating toxins, and you begin to lose weight even if you consume the same amount of calories as before.
  • Your stomach shrinks. Your stomach has a tendency to expand when you’re overweight. As you lose weight, your stomach begins to shrink, which in turn, makes you feel fuller even if you eat smaller portions. And when you eat less, your body will become more sensitive to insulin, the ‘sugar’ hormone. Sugar is a source of calories, but it also plays a crucial role in your body’s chemistry. Your body doesn’t produce it, but it requires that you have enough. When your body hasn’t consumed enough sugar for a long time, it begins to behave in ways that encourage you to eat more. This is why your body tends to accumulate weight even if you avoid dietary sugars and carbohydrates.
  • Your heart rate slows down. It’s been estimated that your resting heart rate can be three to six beats per minute lower when you’re at a healthy weight. Your heart rate slows down as you lose weight because your body becomes less efficient at pumping blood, and thus, you become stronger and less of a strain on the heart. Your pulse becomes weak, and you begin to feel sluggish. Your body also produces less adrenaline as you lose weight, which in turn, makes you tired. This is why it’s been said that your body begins to ‘adapt’ to a thinner frame, and why you might feel like you’re living in a less active world as soon as you reach your target weight.
  • Your sex drive increases. It’s not a secret that men and women differ when it comes to their sex drives. Women’s sex drives are typically higher than those of men. There are several reasons for this, but the most fundamental one has to do with reproduction. As women age, their sex drives tend to diminish. The human body isn’t designed for men to stay young, and this diminishes their sex drive. Men, on the other hand, retain their sexual desires as they get older because their bodies don’t undergo dramatic changes, and this allows them to reproduce. Men’s sex drives increase as they get older too, but not to the degree that women’s do. Once you begin to lose weight, your sex drive increases because your body is changing, and this is likely a result of the above items. You feel better about yourself, and this increases your confidence. It also makes you more attractive to the opposite sex. Your confidence and attractiveness increase your odds of having romantic success, which could result in you gaining weight (in a good way, of course!).
  • You have more energy. As you lose weight, your body produces more energy, which you need to keep up with. You have more energy because it’s easier for your body to use fats as a source of fuel. Even though you’re consuming fewer calories, your body is still getting the nutrients it needs to function properly. It also has more resources to devote to tasks such as digestion and immune function. Your body produces more antibodies as you lose weight too, which it uses to defend itself against invaders such as bacteria and viruses. This is why it’s been said that your body begins to ‘rejuvenate’ upon reaching its target weight.
  • You become less prone to illness. As you lose weight, your body becomes more resistant to diseases and disorders. Studies show that having a healthy weight improves your health, lengthens your life, and decreases your chances of developing a variety of illnesses. The above list details some of the ways in which your body changes as you lose weight, and this is likely why you gain weight after hitting your target weight. Some people are more prone to weight gain than others, and this is mainly due to genetics. If this sounds like you, then there are ways that you can prevent weight gain, and this is what we’ll discuss next.