Available to Premium members, the Smart Macros feature will automatically recalculate your macros goals based on your profile, current weight, and desired macros ratios.
To enable Smart Macros, select Settings from the main (left) navigation menu.
Select the Macros tab.
Finally, scroll down to the Smart Macros section, and toggle the selector to On.
After enabling Smart Macros, note that your goals may vary day-to-day and won't exactly match what you've entered in Settings > Diet Goals, since Smart Macros automatically adjusts based on changes to your profile.
If you've set up a weight goal (Settings > Health Goals), Smart Macros will switch you over to maintenance mode once you meet that weight goal, which may increase your macros goals and your calorie budget.