Why is this Int lagging when its subtracting something over a period of time?

 using UnityEngine;
 using UnityEngine.UI;
 using System.Collections;
 
 
 public class hthScript : MonoBehaviour {
 
     //begining
     public int maxHealth = 100;
     public int maxThirst = 100;
     public int maxHunger = 100;
 
     //realtime
     public int currentHealth;
     public int currentThirst;
     public int currentHunger;
     public float hungerLoss;
     public float thirstLoss;
 
     //references
     public Slider healthSlider;
     public Slider thirstSlider;
     public Slider hungerSlider;
 
 
 
 
 
     // Use this for initialization
     void Start () {
         currentHealth = maxHealth;
         currentThirst = maxThirst;
         currentHunger = maxHealth;
     }
     
     // Update is called once per frame
     void Update () {
         HTHDecline();
 
         healthSlider.value = currentHealth;
         thirstSlider.value = currentThirst;
         hungerSlider.value = currentHunger;
     }
 
 
 
 
 
 
     //when something happens:
     public void TakeDamage(int amount)
     {
         currentHealth -= amount;
     }
 
     public void DrinkWater(int amount)
     {
         currentThirst += amount;
     }
 
     public void EatFood(int amount)
     {
         currentHunger += amount;
     }
 
 
 
 
 
     //Over a period of time:
     public void HTHDecline()
     {
 
         //For hunger
         currentHunger = currentHunger - Mathf.RoundToInt(Time.deltaTime * hungerLoss);
 
         //For thirst
         currentThirst = currentThirst - Mathf.RoundToInt(Time.deltaTime * thirstLoss);
 
         //thirst & hunger kills you:
         if (currentHunger < 25)
         {
             currentHealth = currentHealth - Mathf.RoundToInt(Time.deltaTime * 20);
         }
         if (currentThirst < 25)
         {
             currentHealth = currentHealth - Mathf.RoundToInt(Time.deltaTime * 20);
         }
     }
 }