diff --git a/README.md b/README.md
index 743073eef..4169bad1b 100755
--- a/README.md
+++ b/README.md
@@ -252,6 +252,7 @@ In the Vite Dev mode browsers will typically send out a Warning("Source-Map-Fehl
   * 201: There are parameters missing to create a dish
   * 202: One or more titles haven't been sent
   * 203: There was an error while counting the number of times dishes were taken
+  * 204: The servingSize cannot be adjusted, because there are booked combi-meals
 *CategoryController 3xx*
   * 301: The choosen titles for the category either are missing or do already exist
 *ParticipantController 4xx*
diff --git a/src/Mealz/MealBundle/Controller/MealAdminController.php b/src/Mealz/MealBundle/Controller/MealAdminController.php
index a3cae6020..9fe6f859e 100644
--- a/src/Mealz/MealBundle/Controller/MealAdminController.php
+++ b/src/Mealz/MealBundle/Controller/MealAdminController.php
@@ -213,6 +213,10 @@ private function handleDay(array $day): void
             throw new Exception('106: too many meals requested');
         }
 
+        if (false === $this->dayService->checkMealsUpdatable($dayEntity, $mealCollection)) {
+            throw new Exception('108: Meals must not have participations when being updated');
+        }
+
         $this->dayService->removeUnusedMeals($dayEntity, $mealCollection);
 
         // parentMeal is an array of either one meal without variations or 1-2 variations
diff --git a/src/Mealz/MealBundle/Repository/DishRepository.php b/src/Mealz/MealBundle/Repository/DishRepository.php
index b4166c39f..eeffa7dbc 100644
--- a/src/Mealz/MealBundle/Repository/DishRepository.php
+++ b/src/Mealz/MealBundle/Repository/DishRepository.php
@@ -6,6 +6,7 @@
 
 use App\Mealz\MealBundle\Entity\Dish;
 use App\Mealz\MealBundle\Entity\Meal;
+use App\Mealz\MealBundle\Entity\Participant;
 use App\Mealz\MealBundle\EventListener\LocalisationListener;
 use DateTime;
 use Doctrine\DBAL\Types\Types;
@@ -80,6 +81,43 @@ public function hasDishAssociatedMeals(Dish $dish): bool
         return 0 < $query->getQuery()->getSingleScalarResult();
     }
 
+    /**
+     * @throws NoResultException
+     * @throws NonUniqueResultException
+     */
+    public function hasDishAssociatedCombiMealsInFuture(Dish $dish): bool
+    {
+        $today = new DateTime('today');
+        $formattedDate = $today->format('Y-m-d') . ' 12:00:00.000000';
+
+        $mealRepo = $this->getEntityManager()->getRepository(Meal::class);
+        $participantRepo = $this->getEntityManager()->getRepository(Participant::class);
+        $dayQuery = $mealRepo->createQueryBuilder('m')
+            ->select('DISTINCT d.id')
+            ->join('m.day', 'd')
+            ->join('m.dish', 'g')
+            ->where('g.slug = :slug')
+            ->setParameter('slug', 'combined-dish');
+
+        $mealQuery = $mealRepo->createQueryBuilder('m2')
+            ->select('m2.id')
+            ->where('m2.day IN (' . $dayQuery->getDQL() . ')')
+            ->andWhere('m2.dish = :dishId')
+            ->andWhere('m2.dateTime >= :now')
+            ->setParameter('dishId', $dish->getId())
+            ->setParameter('now', $formattedDate);
+
+        $query = $participantRepo->createQueryBuilder('p')
+            ->select('COUNT(p.id)')
+            ->join('p.meal', 'm3')
+            ->where('m3.id IN (' . $mealQuery->getDQL() . ')')
+            ->setParameter('slug', 'combined-dish')
+            ->setParameter('dishId', $dish->getId())
+            ->setParameter('now', $formattedDate);
+
+        return 0 < $query->getQuery()->getSingleScalarResult();
+    }
+
     /**
      * Counts the number of Dish was taken in the last X Weeks.
      *
diff --git a/src/Mealz/MealBundle/Repository/DishRepositoryInterface.php b/src/Mealz/MealBundle/Repository/DishRepositoryInterface.php
index 1647ac4dc..fe040949f 100644
--- a/src/Mealz/MealBundle/Repository/DishRepositoryInterface.php
+++ b/src/Mealz/MealBundle/Repository/DishRepositoryInterface.php
@@ -17,6 +17,8 @@ public function getSortedDishesQueryBuilder(array $options = []): QueryBuilder;
 
     public function hasDishAssociatedMeals(Dish $dish): bool;
 
+    public function hasDishAssociatedCombiMealsInFuture(Dish $dish): bool;
+
     /**
      * Counts the number of Dish was taken in the last X Weeks.
      */
diff --git a/src/Mealz/MealBundle/Service/DayService.php b/src/Mealz/MealBundle/Service/DayService.php
index 1af3b355a..9d9be4fbf 100644
--- a/src/Mealz/MealBundle/Service/DayService.php
+++ b/src/Mealz/MealBundle/Service/DayService.php
@@ -7,18 +7,22 @@
 use App\Mealz\MealBundle\Entity\Day;
 use App\Mealz\MealBundle\Entity\Meal;
 use App\Mealz\MealBundle\Repository\MealRepositoryInterface;
+use App\Mealz\MealBundle\Repository\ParticipantRepositoryInterface;
 use Doctrine\ORM\EntityManagerInterface;
 
 class DayService
 {
     private MealRepositoryInterface $mealRepository;
+    private ParticipantRepositoryInterface $participantRepo;
     private EntityManagerInterface $em;
 
     public function __construct(
         MealRepositoryInterface $mealRepository,
+        ParticipantRepositoryInterface $participantRepo,
         EntityManagerInterface $entityManager
     ) {
         $this->mealRepository = $mealRepository;
+        $this->participantRepo = $participantRepo;
         $this->em = $entityManager;
     }
 
@@ -60,6 +64,25 @@ public function removeUnusedMeals(Day $day, array $mealCollection): void
         }
     }
 
+    public function checkMealsUpdatable(Day $day, array $mealCollection): bool
+    {
+        $flattenedMeals = array_merge(...array_values($mealCollection));
+        $mealIdsOfCol = array_map(
+            fn ($meal) => $meal['mealId'],
+            $flattenedMeals
+        );
+        $mealsToUpdate = $day->getMeals()->filter(fn ($meal) => false === in_array($meal->getId(), $mealIdsOfCol));
+
+        /** @var Meal $meal */
+        foreach ($mealsToUpdate as $meal) {
+            if (true === $meal->hasParticipations()) {
+                return false;
+            }
+        }
+
+        return true;
+    }
+
     private function removeUnusedMealHelper(Meal $mealEntity, array $mealCollection, Day $day): void
     {
         $canRemove = true;
diff --git a/src/Mealz/MealBundle/Service/DishService.php b/src/Mealz/MealBundle/Service/DishService.php
index dbf28edf2..a6599fb0f 100644
--- a/src/Mealz/MealBundle/Service/DishService.php
+++ b/src/Mealz/MealBundle/Service/DishService.php
@@ -58,8 +58,8 @@ public function isNew(Dish $dish): bool
      */
     public function updateHelper(Dish $dish, array $parameters): void
     {
-        $this->setTitleIfValid($dish, $parameters);
         $this->setServingSizeIfValid($dish, $parameters);
+        $this->setTitleIfValid($dish, $parameters);
         $this->setDescriptionIfValid($dish, $parameters);
         $this->setCategoryIfValid($dish, $parameters);
         $this->setDietIfValid($dish, $parameters);
@@ -119,6 +119,10 @@ private function setDescriptionIfValid(Dish $dish, array $parameters): void
     private function setServingSizeIfValid(Dish $dish, array $parameters): void
     {
         if (true === $this->apiService->isParamValid($parameters, 'oneServingSize', 'boolean')) {
+            if (true === $this->hasCombiMealsInFuture($dish)) {
+                throw new Exception('204: The servingSize cannot be adjusted, because there are booked combi-meals');
+            }
+
             $dish->setOneServingSize($parameters['oneServingSize']);
             if (true === $dish->hasVariations()) {
                 /** @var Dish $variation */
@@ -138,4 +142,9 @@ private function setTitleIfValid(Dish $dish, array $parameters): void
             $dish->setTitleEn($parameters['titleEn']);
         }
     }
+
+    private function hasCombiMealsInFuture(Dish $dish): bool
+    {
+        return $this->dishRepository->hasDishAssociatedCombiMealsInFuture($dish);
+    }
 }
diff --git a/src/Resources/src/locales/de.json b/src/Resources/src/locales/de.json
index e583998e2..f83a399e2 100644
--- a/src/Resources/src/locales/de.json
+++ b/src/Resources/src/locales/de.json
@@ -159,6 +159,7 @@
       "201": "Es fehlen noch Informationen um das Gericht estellen zu können.",
       "202": "Ein oder mehrere Titel für das zu erstellende Gericht scheinen zu fehlen.",
       "203": "Es gab einen fehler beim zählen, wie häufig einzelne Gerichte bestellt wurden.",
+      "204": "Das Gericht kann nicht aktualisiert werden, da es in gebuchten Kombi-Meals enthalten ist.",
       "301": "Die gewählten Titel für die Kategorie fehlen oder existieren schon.",
       "401": "Um einen Benutzer zu einem Kombi-Gericht hinzuzufügen, müssen zwei Gerichte ausgewählt werden.",
       "402": "Etwas ist beim Buchen der Mahlzeit schiefgegangen.",
diff --git a/src/Resources/src/locales/en.json b/src/Resources/src/locales/en.json
index 6002272d9..08afc4dbf 100644
--- a/src/Resources/src/locales/en.json
+++ b/src/Resources/src/locales/en.json
@@ -159,6 +159,7 @@
       "201": "Information is still missing to be able to create the dish.",
       "202": "One or more titles for the dish being created appear to be missing.",
       "203": "There was an error when counting how often individual dishes were ordered.",
+      "204": "The dish can't be updated, because there are booked combi-meals containing it.",
       "301": "The selected titles for the category are missing or already exist.",
       "401": "To add a user to a combined meal, two dishes must be selected.",
       "402": "Something went wrong while booking the meal",