How Your Body Will Change During Weight Loss

by Ahmed Zayed, MD on March 4, 2020
Last updated on May 23, 2021

Your body goes through a lot of changes, such as changes to muscle tissue, hormone levels, body mass, and fat tissue, during weight loss. Weight loss aims not only to reduce calories but also to maintain physical activities as well as certain nutrients such as calcium, vitamin D, and protein which can prevent the loss of bones and muscles during the process. 

A blonde woman working out at the gym

Here are the ten surprising things that will happen to your body during weight loss

Body Fat Changes

As you lose weight, the fat tissues in your body are reduced. The harmful belly fats in your skin become less dangerous. A study has shown that weight loss can reduce a large portion of the intra-abdominal fat than the subcutaneous fat. But this is better because intra-abdominal fats are linked with various metabolic diseases, and losing weight can lessen your risk of obesity (1).

Bone and muscle changes

Your body composition includes bones and muscles. Losing weight can make changes in your bones and muscles. A study has shown that people who diet can have decreased their muscle mass. But those who include exercise in their diet not only reduced their muscle mass but also prevented the loss of their muscles (2)

Losing weight can also affect your bone mineral density. Another study revealed that people who lose modest amounts of weight also minimized their bone mass even if they already engaged themselves with low-impact exercises (3)

Changes in hormones

Leptin is reduced when you lose weight. Leptin is a hormone that is directly linked to fats and obesity. This hormone is responsible for sending signals in your brain and for maintaining your body weight. Since leptin comes from fat cells, it is connected with body fats. Leptin is directly proportional to body fats, so as the former increases, the latter also increases (4)

But this situation can make it hard for you to maintain your weight as your brain will make its way to keep the leptin levels as it is. This will most likely result in reduced energy expenditure and increased feeding. A study has shown that people who lose weight experience decreased satiety and increased hunger. But administering leptin injections can help in reversing the effects of weight loss (5)

Another study has shown how body fats increase the levels of estrogen and other hormones. The hormone levels also drop during weight loss. And since these hormones are linked to menstrual cycles and mood, it was reported that people who lose weight experience changes in their menstrual cycles and mood (6). 

Effects in nutrition

Your body composition is affected by your nutrition. If you have the right kind of diet plus regular exercise, you can experience a fat loss rather than other kinds of body mass. A study has shown that a low-calorie diet with protein supplementation can help promote fat loss. Additional intake of vitamin D and calcium also helps reduce the loss of bone density due to weight loss.   

Your diet might also help you lose weight, but this may not provide you with enough nutrients your body needs. Your diet may help you reduce weight at first, but its effect may not be on a long term basis. Remember that your body needs vitamins, minerals, as well as fats to make it work properly and maintain weight (7)

You will have less tolerance with cold environments

When you lose weight, you will observe that you feel cold most of the time. This is because your body used to have insulating fats which keep it warm. But as you lose weight, insulating fats are reduced, that is why you become more sensitive to cold temperatures. 

Furthermore, some essential fats should compose at least 2 to 4 percent for men and 10 to 12 percent for women to help maintain basic bodily functions. These fats can protect your internal organs, insulate your body, and help in absorbing vitamins. These also produce energy to keep you warm from the moment they sense a cooler temperature (8).  

Your skin might sag

Your skin is made of proteins-collagen and elastin. Protein fibers help in keeping your skin maintain its elastic and firm strength. That is the reason why if you gain weight, your skin stretches without tearing it. But as you gain weight, these protein fibers weaken that is why it becomes damaged over time. 

And if you experience a significant weight loss, it can be hard for these proteins to go back to their original state. Indeed, the skin is elastic; that is why it can form the shape of your body. But a sudden weight loss may find it hard for your skin to go back to a smaller shape, which results in sagging (9)

You might experience fewer headaches

The American Migraine Foundation held that obesity makes you at about 50 percent at risk of migraine. As obesity increases, chances also increase. That is the reason why if you have a BMI of more than 40, it makes you at 275 percent at risk of migraine. Although migraine is not caused by obesity, it is a risk factor that could be prevented if you lose weight (10).

It was shown that the main reason why weight and migraines are connected is that the fat cells are responsible for triggering inflammation, which might result in a migraine. But if you lose weight, these fat cells are reduced, which also decreases the level of inflammation in your body. 

You will get a good sleep

People who are overweight are 45 percent at a higher risk of sleep apnea. It is a condition which disrupts your breathing and interrupts your sleep at most 30 times in an hour. And people who have this condition are most likely to die due to cardiovascular problems (11)

But if you lose weight, chances of sleep disruptions decrease (12).  Furthermore, those who lose weight usually allot their time to exercise. Exercise plus diet can help in giving you a better quality of sleep. 

You will have an improved self-esteem

There are many reasons why losing weight can help improve your self-esteem. Most people who are overweight tend to feel bad about their bodies. But shedding those pounds could make you feel good about yourself. Not only will it make you fit your clothes, but it can help improve your physical appearance, which can boost your self-esteem. 

And since there are many positive effects when you lose weight, you will feel better. For instance, you get the right amount of sleep. If you sleep better at night, you will become more energized for the rest of the day. This will also allow you to engage in various physical activities that can produce feel-good chemicals such as endorphins (13)

You will be more cautious with what you eat

You will find it hard to eat anywhere, especially if you have a specific diet meal plan. Maintaining your weight also requires you to sustain your diet. If you are counting calories, then you should need to be cautious with what you eat.

Other people find it a drag to ask how dishes are prepared or about the ingredient list every time you are out. And in the end, you find restaurants to be less appealing because of the salt, fat, and sugar that you need to avoid (14)

How Much Weight Can You Lose?

Healthy weight loss does not happen overnight. Your body undergoes a lot of changes as you lose weight. Experts suggest that losing around 1 to 2 pounds of weight a week is healthier and can keep your weight off (15).

Here is what happens to your body in the first week

In the first week, you are expected to establish a healthy habit, follow a nutrition plan, and workout regularly. These are just a few ways on how you create a calorie deficit every day for a week. And since your body needs energy, it breaks down stored energy such as from fats and glycogen. 

Glycogen serves as energy storage usually found in your muscles and liver. If your blood sugar level decreases or if you perform strenuous exercises, glycogen is converted into glucose.  Since glycogen comes with water, it goes with it once it is converted to glucose, and that is mostly experienced by people who have a rapid weight loss (16)

Here is what happens to your body in the first month

In the first month of losing weight, your body usually loses water, glycogen, fats, and muscle tissues. This typically depends on the kind of activities you engage in to lose weight. And as you are losing weight, your fat cells become smaller. The fats in the cells are broken down and serve as fuel by your internal organs (17)

The waste products of this chemical reaction are water and carbon dioxide, which you get rid of your body through sweat, urine, and other bodily fluids. Take note that even if you lose weight, your body still contains several fat cells. But as these fat cells become smaller, fewer leptins are released. 

Leptins, as we already discussed, are hormones that help in maintaining your diet. It signals your body to stop eating when you are full. If your body contains fewer leptins, you will become hungrier. Experts recommend including lean protein and fiber such as whole grains, fruits, and vegetables in your diet (18)

Aside from that, your muscle mass may also be reduced. And this is something which we supposed no one wants to lose. If you don’t want this to happen, it is recommended to engage in high-intensity interval training, as well as strength-training routine, to keep your muscle mass. 

Benefits of Weight Loss

Well, it’s time for you to get rid of your big pants. Here are other things that you need to know about the benefits of weight loss (19):

Better sleep

Yes, we already mentioned it earlier. Just come to imagine how losing even just 5 percent of your weight can give you a good night’s sleep. Less stress and more energy can make you more productive at work. 

Improved sex drive

If you lose weight, you will not feel tired all the time. It also helps in boosting your testosterone level and increasing your libido. Not just that, it can improve your sexual performance and increase your satisfaction in bed. 

Better mood

Losing weight does not only improve your physical appearance, but it also enhances mental fitness. Endorphins are hormones that help in maintaining a positive feeling. You know how mood affects your entire day, right?

Clearer and brighter skin

If you lose weight, you will not only slim down and get healthy. Your skin will most likely glow as it becomes clearer and brighter. This will happen only if your body obtains the right nutrients, such as from fruits and vegetables, which are also responsible for weight loss. 

Less stress

Exercise and a healthy diet are linked to stress. Exercise is known to reduce stress, the same way with a healthy diet. You can alleviate stress and anxiety if you get rid of those unwanted pounds, especially that exercise and a healthy diet can affect you physically, emotionally, and psychologically. 


Losing weight is ideal for many, especially for those who are overweight. However, not all weight loss can give positive effects to your body. But it is more of a positive though. Your body will undergo a lot of changes during weight loss. The changes may or may not be favorable as time goes by. But then remember how losing weight can benefit your entire well-being. 


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