This is absolutely false. The human body must always consume a minimum amount of energy for basic maintenance. See https://en.wikipedia.org/wiki/Basal_metabolic_rate. While it does vary it also has a hard lower limit.
The basic metabolic rate varies between individuals. One study of 150 adults representative of the population in Scotland reported basal metabolic rates from as low as 1,027 kilocalories (4,300 kJ) per day to as high as 2,499 kilocalories (10,460 kJ); with a mean BMR of 1,500 kilocalories (6,300 kJ) per day.
When I typed that I was thinking of the basal metabolic rate, which is relatively constant for a person. Think of it as the calories a coma patient would need to stay alive.
The basic metabolic rate varies between individuals. One study of 150 adults representative of the population in Scotland reported basal metabolic rates from as low as 1,027 kilocalories (4,300 kJ) per day to as high as 2,499 kilocalories (10,460 kJ); with a mean BMR of 1,500 kilocalories (6,300 kJ) per day.