When it comes to reducing the risk of all-cause mortality, improving mental health and improving sleep quality, the World Health Organization (WHO) lacked recommendations for physical activity.
- Then, as now, the organization recommended that people ages 18 to 64 get at least 150 minutes a week of moderate aerobic physical activity, or 75 minutes if it’s vigorous.
- Recently, the organization changed this maximum to a minimum for those who want to enjoy these extra health benefits.
- Coincidentally, this is the same 300 minutes (5 hours) from which someone could start losing weight regardless of food.
Kyle Flack, professor of nutrition at the University of Kentucky (USA), states this number in a study he published in the journal Medicine & Science in Sports & Exercise: “If our goal is to lose weight, we need to burn more than 1,000 calories per week.
More precisely, allow yourself at least 5 hours of moderate-intensity exercise if we do not want to make major changes in diet.” According to the findings of the research, the explanation is that these 1000 calories are the maximum energy that the body needs after exercise as caloric compensation.
This means that for a person who burns 1,500 calories and does not control what he eats, the body will ask him to take in 1,000 calories to compensate for the effort, exactly the same number that it will ask of a person who has burned twice as much.
With this compensatory ceiling, the total caloric expenditure in the first example would be 500 calories, while in the second example it would increase to 2,000.
To reach this curious conclusion, the researchers recruited 44 men and women, all of whom had a sedentary lifestyle and were overweight (something you have to remember), took blood and monitored the levels of certain hormones that control appetite. Half of them were instructed to exercise twice a week, for at least an hour and a half, until they burned 750 calories per session, either running or walking.
1500 calories total
The other half trained for 40 to 60 minutes, six times a week, burning 500 calories per session until they reached twice as much as the first group (3,000 calories). After 12 weeks, the researchers observed that leptin, a hormone responsible for the feeling of fullness, decreased in the 3,000-calorie group – but not in the other – suggesting that the participants were better able to control food cravings.
The explanation is complicated. “When we lose weight for some reason and lose body fat, leptin decreases, so hunger is triggered and we eat more to replace the lost weight. It’s a natural mechanism to maintain weight,” explains Susana Monereo, head of the Endocrinology and Nutrition Service at the Gregorio Marañón General University Hospital in Madrid and secretary general of the Spanish Society for the Study of Obesity.
However, “when we lose weight ―obese individuals with high levels and high resistance to this hormone at the brain level― in the form of fat, after exercise, the sensitivity of this hormone at the brain level improves and compensatory hunger does not occur, even if leptin is withdrawn.
Individuals who experience this decrease have greater weight loss than those who do not.
“It’s probably more important to eat less in the initial phase of weight loss and exercise more in the maintenance phase,” says endocrinologist Susana Monereo. “It’s probably more important to eat less in the initial phase of weight loss and exercise more in the maintenance phase,” says endocrinologist Susana Monereo. ).
Monereo cautions that the study has its limitations because, apart from a very small sample, it is based on an assumption that is difficult to translate into the real world: that overweight, sedentary people will be able to start training overnight for six days and a week at a high intensity.
- Much less, if they have to adjust to the levels that she herself points out could be used for weight loss without depending on more factors than exercise, levels even higher than in the new study:
- “One hour a day, at least six days a week, would be ideal, and with some intensity, you can get your heart rate up after combining aerobic exercise with strength and resistance exercises.”