Photo by iStock
When the pointer goes down on the scale, have you lost fat or muscle mass? What can you do to not regain the weight you lost? Research provides the answers.
The global weight loss market – including products and services – was estimated in 2022 at an amount greater than 161 billion euros. It is expected to exceed 250 billion by 2028.
Since September is approaching, which is traditionally the month of goals ( from Monday we will start a diet , from Monday we will go to the gym, etc.), let’s see what happens to our body when we lose weight, with the help of Rebecca Valdez , nutritionist and nutrition communication consultant.
Where does fat go when we lose weight?
When we eat healthy and exercise, fat is turned into energy through various processes and two by-products are produced: water and carbon dioxide.
- Water is “expressed” in our sweat and urine.
- Carbon dioxide comes out of us with exhalation. It is how 84% of the fat we lose leaves us.
How does fat become water and carbon dioxide?
- The brain signals the fat cells to release the energy packets (fatty acid molecules) into the bloodstream.
- The muscles, lungs, and heart pick up these fatty acids, break them down, and use the energy stored in the bonds to carry out their activities.
- The residues that remain are discarded as part of the breath, in the exhaled carbon dioxide, or in the urine.
This leaves the fat cell empty and renders it useless . Cells actually have a short lifespan, so when they “die” the body absorbs what’s left and doesn’t replace it.
Over time, the body directly extracts the energy (i.e. calories ) from food to the organs that need it, instead of storing it first. As a result, the body adjusts by reducing the number and size of fat cells , which then improves basal metabolism , reduces inflammation, fights disease, and extends life.
Losing fat or muscle mass?
When we don’t meet our nutritional needs, the body goes into defense mode and turns first to its glycogen reserves, then to muscles and then to fat . Consequently, with weight loss, a percentage of fat-free mass (see lean mass) is lost, which may include water, skeletal muscle, or even bone mass.
The percentage of fat mass versus fat-free mass that is lost is something that depends on different factors.
A 2018 study had informed that:
- Participants who lost weight through calorie restriction had a reduction in lower limb lean mass.
- Those who achieved weight loss through exercise maintained their fat-free mass.
Another study highlighted that there are categories of people who are at particular risk of losing fat-free mass during weight loss , including postmenopausal women, the elderly, those with metabolic disease, and athletes. So, it’s helpful to consult with professionals and not make up our own minds – or something that has worked for another organisation.
What happens when we lose weight?
Research has shown that losing a small percentage of our body weight, 5-10%, can improve blood pressure, cholesterol and blood sugar levels . Improved blood markers can help us reduce the risk or better manage chronic and metabolic diseases, such as cardiovascular disease and diabetes.
Work from 2018 also confirmed that losing weight improves our psychology. Initial weight loss led participants to report a better quality of life , including increased self-esteem and improved physical, work and sex life, while reducing their social anxiety.
The other side of the coin is that once we’ve lost weight we need to keep doing certain things to keep it off.
In 29 long-term studies done in the US, it appeared that more than 50% regained the weight within two years of losing it . A percentage greater than 80% recovered it in five years. As a “key” to success it was proposed to forget the restrictions and focus on a balanced and nutritious diet , with things we like, which will consequently be easier to stick to.
It has also been found that maintaining long-term weight loss is extremely difficult due to biological, behavioral and environmental factors , with fluctuations being dangerous to our health.
