Can some one help me with my C# script? (HUD)

 hello, i make a little survival game, and i make a hud system, but i can’t finish it, because i don’t know how, ia have to add the food system and stamina to my hud, if you can help me i will be very happy.
 This is The HUD
 using UnityEngine;
 using System.Collections;
 using UnityEngine.UI;
 public class HUD : MonoBehaviour {
 //Health
 public Image health;
 public float HealthPercentage;
 //Hunger
 public Image hunger;
 public float HungerPercentage;
 //Thirst
 public Image thirst;
 public float ThirstPercentage;
 //Stamina
 void Start()
 {
 HungerPercentage = 0.9f;
 ThirstPercentage = 0.9f;
 HealthPercentage = 1f;
 }
 // Update is called once per frame
 void Update ()
 {
 //Hunger
 HungerPercentage -= 0.002f * Time.deltaTime;
 HungerPercentage = Mathf.Clamp (HungerPercentage, 0, 1);
 hunger.fillAmount = HungerPercentage;
 //Thirst
 ThirstPercentage -= 0.0025f * Time.deltaTime;
 ThirstPercentage = Mathf.Clamp (ThirstPercentage, 0, 1);
 thirst.fillAmount = ThirstPercentage;
 //Stamina
 //Health
 if ((HungerPercentage <= 0) && (ThirstPercentage <= 0)) {
 HealthPercentage -= 0.0025f * Time.deltaTime;
 health.fillAmount = HealthPercentage;
 } else {
 if ((HungerPercentage <= 0) || (ThirstPercentage <= 0)) {
 HealthPercentage -= 0.0025f * Time.deltaTime;
 health.fillAmount = HealthPercentage;
 }
 }
 }
 }