Ayurveda, the traditional Indian science of life and wellness, places food (Āhāra) at the centre of physical as well as psychological well-being. Classical treatises including the Caraka Saṁhitā and Suśruta Saṁhitā describe food not simply as nourishment for survival, but as a therapeutic tool capable of maintaining the harmony of doṣa, dhātu and agni. This study explores the key nutritional concepts of Ayurveda such as āhāra-vidhi (proper rules of diet), āhāra-vidhi-viśeṣa-ayatana (determinants of ideal food intake), and the relationship between triguna, tridosha and prakṛti. Particular attention is given to the division of food into sāttvika, rājasika, and tāmasika categories and their psychological effects, along with the Ayurvedic parameters of vīrya (potency), vipāka (post-digestive effect) and prabhāva (specific action). The paper also evaluates the modern scientific relevance of these Ayurvedic principles in the areas of metabolism, gut microbiome balance, immunity and dietary therapy. The overall conclusion highlights that Ayurveda views food as a powerful form of medicine, and that adherence to a diet matched with seasonal changes, individual body constitution and digestive strength promotes longevity, prevents disease, and nurtures mental and emotional health.