diff --git a/src/cronometer_api_mcp/client.py b/src/cronometer_api_mcp/client.py
index d645527..928db09 100644
--- a/src/cronometer_api_mcp/client.py
+++ b/src/cronometer_api_mcp/client.py
@@ -728,14 +728,29 @@ def create_custom_food(
                 "defaultMeasureId": 0,
                 "comments": None,
                 "alternateId": None,
+                # The first measure becomes the server-assigned default.
                 "measures": [
                     {
                         "id": 0,
                         "name": serving_name,
                         "value": serving_grams,
                         "amount": 1.0,
-                        "type": "Atomic",
-                    }
+                        "type": "Weight",
+                    },
+                    {
+                        "id": 0,
+                        "name": "g",
+                        "value": 1.0,
+                        "amount": 1.0,
+                        "type": "Weight",
+                    },
+                    {
+                        "id": 0,
+                        "name": "oz",
+                        "value": _OZ_GRAMS,
+                        "amount": 1.0,
+                        "type": "Weight",
+                    },
                 ],
                 "labelType": "AMERICAN_2016",
                 "nutrients": nutrients,
diff --git a/tests/test_client.py b/tests/test_client.py
index f7deff8..4aa9894 100644
--- a/tests/test_client.py
+++ b/tests/test_client.py
@@ -868,10 +868,40 @@ def test_import_recipe_rejects_blank_input(tmp_path, monkeypatch):
 
 
 # ---------------------------------------------------------------------------
-# create_custom_food: extra_nutrients
+# create_custom_food
 # ---------------------------------------------------------------------------
 
 
+@pytest.mark.parametrize("serving_grams", [100.0, 200.0])
+def test_create_custom_food_supports_weight_units(tmp_path, serving_grams):
+    client, state = make_cold_client(tmp_path, [{"result": "SUCCESS", "id": 555}])
+
+    client.create_custom_food(
+        "Test Food",
+        calories=200,
+        protein_g=10,
+        fat_g=5,
+        carbs_g=20,
+        serving_name="plate",
+        serving_grams=serving_grams,
+    )
+
+    data = state["payloads"][0]["data"]
+    serving, grams, ounces = data["measures"]
+    assert [m["name"] for m in data["measures"]] == ["plate", "g", "oz"]
+    assert all(m["type"] == "Weight" for m in data["measures"])
+    assert all(m["amount"] == 1.0 for m in data["measures"])
+    assert serving["value"] == serving_grams
+    assert grams["value"] == 1.0
+    assert ounces["value"] == pytest.approx(28.3495231)
+
+    nutrients = {n["id"]: n["amount"] for n in data["nutrients"]}
+    assert nutrients[208] == 200 * 100 / serving_grams
+    assert nutrients[203] == 10 * 100 / serving_grams
+    assert nutrients[204] == 5 * 100 / serving_grams
+    assert nutrients[205] == 20 * 100 / serving_grams
+
+
 def test_create_custom_food_extra_nutrients_payload(tmp_path):
     """extra_nutrients are appended, normalized to per-100g like the macros."""
     client, state = make_cold_client(tmp_path, [{"result": "SUCCESS", "id": 555}])
diff --git a/tests/test_custom_food_edit.py b/tests/test_custom_food_edit.py
index 1a3eff2..e66e1f8 100644
--- a/tests/test_custom_food_edit.py
+++ b/tests/test_custom_food_edit.py
@@ -168,6 +168,34 @@ def test_update_custom_food_serving_overrides_measure_and_scale(tmp_path):
     assert nutrients_by_id(state["payloads"][1])[208] == 200.0  # 400 per 200 g
 
 
+def test_update_custom_food_preserves_weight_units(tmp_path):
+    food = custom_food()
+    food["measures"][0]["type"] = "Weight"
+    weight_units = [
+        {"id": 901, "name": "g", "amount": 1, "value": 1, "type": "Weight"},
+        {
+            "id": 902,
+            "name": "oz",
+            "amount": 1,
+            "value": 28.3495231,
+            "type": "Weight",
+        },
+    ]
+    food["measures"].extend(dict(unit) for unit in weight_units)
+    client, state = make_cold_client(tmp_path, [food, OK])
+
+    client.update_custom_food(
+        FOOD_ID, serving_name="plate", serving_grams=200, calories=400
+    )
+
+    data = state["payloads"][1]["data"]
+    assert data["defaultMeasureId"] == 900
+    assert data["measures"][0]["id"] == 900
+    assert data["measures"][0]["value"] == 200
+    assert data["measures"][1:] == weight_units
+    assert nutrients_by_id(state["payloads"][1])[208] == 200
+
+
 def weight_default_food() -> dict:
     """A food first saved as "400 g": its default measure is 400 units of a
     Weight measure, which the app renders as "400 <name>"."""