If one is able to control the tongue then one is understood to be in full control of all the senses.

“By eating, one gives energy and activity to all of the senses, and thus if the tongue is uncontrolled all of the senses will be dragged down to the material platform of existence. Therefore, by all means one must control the tongue. If one fasts, then all of the other senses become weak and lose their potency. The tongue, however, becomes more greedy to taste delicious preparations, and when one finally indulges the tongue, all of the senses quickly go out of control. Therefore, Śrīla Viśvanātha Cakravartī Ṭhākura advises that one accept mahā-prasādam, or the remnants of the Lord’s food, in a moderate proportion. Since the tongue’s function is also to vibrate, one should vibrate the glorious holy name of the Supreme Lord and taste the ecstasy of pure Kṛṣṇa consciousness. As stated in Bhagavad-gītā, rasa-varjaṁ raso ’py asya paraṁ dṛṣṭvā nivartate: only by the higher taste of Kṛṣṇa consciousness can one give up the deadly lower taste that keeps one imprisoned in material bondage.

Śrīla Bhaktisiddhānta Sarasvatī Ṭhākura states that as long as one’s intelligence is materially covered, one cannot understand the pleasure of Kṛṣṇa consciousness. Trying to enjoy without Kṛṣṇa, the living entity leaves the abode of the Supreme Lord, called Vrajabhūmi, and comes down into the material world, where he quickly loses control of his senses. One becomes particularly victimized by the tongue, belly and genitals, which exert intolerable pressure on the conditioned soul. These desires subside, however, when one reestablishes one’s blissful relationship with the Lord, who is actually the reservoir of all pleasure. One who is attached to the taste of Kṛṣṇa consciousness automatically follows all of the rules and regulations of religious life due to spontaneous attraction to viśuddha-sattva, or the mode of pure goodness. Without such spontaneous attraction, one is certainly bewildered by the pushing of the material senses.

Even the beginning stage of devotional service, called sādhana-bhakti (regulatory practice), is so powerful that it brings one to the platform of anartha-nivṛtti, where one becomes free from unwanted sinful habits and gains relief from the pressure of the tongue, belly and genitals. Thus one is delivered from the bondage of material addiction and can no longer be cheated by the allurements of the material energy. As it is said, all that glitters is not gold. In this regard Śrīla Bhaktisiddhānta Sarasvatī Ṭhākura recommends that we consider the following song written by his father, Śrīla Bhaktivinoda Ṭhākura:

śarīra avidyā-jāl, jaḍendriya tāhe kāl, jīve phele viṣaya-sāgare
tā’ra madhye jihvā ati, lobhamay sudurmati, tā’ke jetā kaṭhina saṁsāre
kṛṣṇa baḍa dayāmay, karibāre jihvā jay, sva-prasādānna dila bhāi
sei annāmṛta pāo, rādhā-kṛṣṇa-guṇa gāo, preme ḍāko caitanya-nitāi

“O Lord, this material body is a lump of ignorance, and the senses are a network of paths to death. Somehow, we have fallen into this ocean of material sense enjoyment, and of all the senses the tongue is most voracious and uncontrollable; it is very difficult to conquer the tongue in this world. But You, dear Kṛṣṇa, are very kind to us and have given us such nice prasādam, just to control the tongue. Now we take this prasādam to our full satisfaction and glorify Their Lordships Śrī Śrī Rādhā-Kṛṣṇa, and in love call for the help of Lord Caitanya and Lord Nityānanda.”

Source: A.C. Bhaktivedanta Swami Prabhupada (2014 edition), “Srimad Bhagavatam”, Eleventh Canto, Chapter 08 – Text 21.