B.G 4.30
अपरे नियताहाराः प्राणान् प्राणेषु जुह्वति। सर्वेऽप्येते यज्ञविदो यज्ञक्षपितकल्मषाः ॥३०॥
apare niyatāhārāḥ prāṇān prāṇeṣu juhvati। sarve'pyete yajñavido yajñakṣapitakalmaṣāḥ ॥30॥
Still others regulating food offer the life force into life force. All these are indeed knowers of Yajna, and have their impurities cleansed by Yajna.
Gīta Bhāshya 4.30
"Offering life force onto life force" - means limiting the consumption of food.
By regulating the diet alone, the weakening of the life force occurs, and life force is offered into life force.
"Control speech with mind, and mind with wisdom..." (kaṭhopaniṣad 1.3. 13)
Such Vedic testimonials confirm its accuracy. Other testimonials also confirmed it, such as:
"Indeed, by consuming a small quantity of food, life force is offered into the life force."
- thus.