B.G 4.30
अपरे नियताहाराः प्राणान् प्राणेषु जुह्वति। सर्वेऽप्येते यज्ञविदो यज्ञक्षपितकल्मषाः ॥३०॥
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.
नियताहारत्वेनैव प्राणशोषात् प्राणान् प्राणेषु जुह्वति।
By regulating the diet alone, the weakening of the life force occurs, and life force is offered into life force.
"यच्छेद्वाङ्मनसी प्राज्ञः" (कठोपनिषद् १.३. १३)
"Control speech with mind, and mind with wisdom..." (kaṭhopaniṣad 1.3. 13)
इत्यादि श्रुत्युक्त प्रकारेण वा। अन्यदपि ग्रन्थान्तरे सिद्धम्-
Such Vedic testimonials confirm its accuracy. Other testimonials also confirmed it, such as:
"यदस्याल्पाशनं तेन प्राणाः प्राणेषु वै हुताः"
इति ॥३०॥
"Indeed, by consuming a small quantity of food, life force is offered into the life force."
- thus.