How to lose body fat after eating below maintenance cal for 4 years

Been eating below maintenance calories for probably 4 years now without ever realising, mainly with the intention of "slowly" losing weight. Have maintained weight since. Am hoping to reduce body fat but unsure how to go about this properly due to eating below maintenance calories for so long.

Maintenance calories are suggested by: omnicalculator . com
Typical calories consumed per day: 800-1200
Typical calories burned per day: 400

Have recently started HIIT training 5-6 days a week and tracking calories more closely (which I was doing previously too but not as specifically). Am on a full plant-based diet and have been for about 6 years. I almost never eat "take-out" and diet mainly consists of: veggies, bread, tofu, beans, "healthy" snacks.

Goal is to: lose weight (about 10 kg) and increase muscle mass thru training.
Female, 23, 153cm, 60-62kg, fit, go for regular walks/runs, regular HIIT, eat well.

How much weight have you lost in those 4 years?

[QUOTE=TolerantLactose;1645014453]How much weight have you lost in those 4 years?[/QUOTE]

Maybe 1-2kg maximum. Have pretty much maintained same weight over the 4 years.

[QUOTE=rhnestonecowgrl;1645034583]Maybe 1-2kg maximum. Have pretty much maintained same weight over the 4 years.[/QUOTE]
Then you weren't really below maintenance.

The amount you were eating in that time was maintenance. This is effect of homeostasis. Your appetite is a powerful force that tends to adjust to keep your body weight at a constant level.

Calculators are just guesswork. If you know how much you were eating on average per day to maintain your weight then deduct 2-500 calories from that... easy.

This seems to me very interesting because based on your calorie consumption you are very undereating, however your height is 153 cm so I should keep that in mind. I would highly suggest changing up your training as soon as possible. HIIT training 5-6 days a week is too much and can wreck your metabolism because it tires your body without resting. 2 times a week HIIT, 2 times a week Low intensity like pilates or yoga with daily walks would make a huge difference, trust me. And you should definitely increase your protein intake.