1-Foods that cause inflammation should be avoided

Certain meals slow down digestion and increase free radical damage, which accelerates the aging process. These are what are known as "metabolism death foods." Processed and inflammatory foods are seen by the body as poisons, so eating them activates your innate immune system which raises stress hormone production and decreases metabolic performance. Unfortunately, even "healthy" foods can cause undesirable weight gain, thyroid dysfunction, chronic weariness, hormone imbalance, and intestinal irritation.

advocate avoiding as much as possible the following foods:

Sugary beverages (including soda and juices)Grain-based processed meals, particularly those containing gluten (including wheat products like bread, pasta, cereal, crackers, muffins, desserts, flours, chips, and granola bars)

vegetable oils that have been refined

ingredients and artificial sweeteners

dairy and animal products of poor quality (the kind that is not grass-fed, pasture-raised, raw, and organic)

2-Stop dieting. Provide your body with the calories it requires

If you've ever been on a diet before, you've probably observed that you're more cranky, lethargic, and potentially even sick. These are symptoms that your metabolism is slowing down. Keep your body properly fuelled, on the other hand, and it will perform far better in all areas of life.

If you are in a calorie deficit due to excessive exercise and insufficient food intake, your metabolism receives the message that it must slow down all functions to conserve energy. You may find yourself in a catabolic state known as "starvation mode," which triggers hormonal and cellular changes that increase your hunger and thirst while reducing your fat-burning and muscle-building abilities.

It's vital to eat enough calories every day, especially when they come from a range of unprocessed whole foods, for cognitive, hormonal, sexual, and digestive health. People who eat properly and avoid yo-yo dieting have better digestion, are more motivated, have a stronger desire to be active, have better mental health, have a stronger sex drive, and have more stable blood sugar levels. When you eat enough, you are more likely to be active, acquire strength and muscle mass faster, and feel less tired.

3-High-intensity interval training (HIIT) 

Any type of exercise is vital for maintaining metabolic function as you get older. while metabolism often diminishes as people age, this isn't always the case if you keep active and preserve muscle mass. There was no significant difference in resting metabolic rate between groups of young and older physically active  who were matched for exercise volume and estimated energy intake,   While a fall in metabolism appears to be most closely linked to age-related decreases in exercise 

volume and calorie consumption, it does not always occur in those who exercise regularly and eat enough to meet their needs.

4-Get a Lot of Sleep

There's a documented correlation between a healthy metabolism and having enough sleep and rest.IF not getting enough sleep can lead to weight gain. Because the body strives to preserve energy when it is exhausted, can significantly slow down your metabolism. Make getting seven to nine hours of sleep a priority every night to keep hormone levels in line, particularly cortisol, which causes the body to store extra fat.

5-Foods that Boost Metabolism

Certain foods may improve the body's ability to utilize and waste energy. This is due to the thermic effects of some foods, which means that the body needs to work harder to break down and metabolize certain fat-burning foods, in some cases because the food has a warming effect on the body that burns calories.

A powerful metabolism is linked to eating enough protein, spicy meals, and drinking natural forms of caffeine in moderation, such as coffee or tea.

6-Begin to Lift Weights

Lifting weights increases lean muscle mass, which burns more calories than body fat. This helps to increase the resting metabolic rate. Gaining muscle entails increasing the amount of metabolic effort your body must perform daily merely to keep you alive, as muscular tissue is more active than fat.