diff --git a/gallery_dl/extractor/instagram.py b/gallery_dl/extractor/instagram.py
index 6213e9ac..4c01c003 100644
--- a/gallery_dl/extractor/instagram.py
+++ b/gallery_dl/extractor/instagram.py
@@ -223,7 +223,8 @@ class InstagramExtractor(Extractor):
         for num, item in enumerate(items, 1):
 
             try:
-                image = item["image_versions2"]["candidates"][0]
+                candidates = item["image_versions2"]["candidates"]
+                image = candidates[0]
             except Exception:
                 self.log.warning("Missing media in post %s",
                                  data["post_shortcode"])
@@ -239,6 +240,22 @@ class InstagramExtractor(Extractor):
                 video = None
                 media = image
 
+                if len(candidates) <= 3:
+                    self.log.warning(
+                        "%s: Image candidate list possibly incomplete "
+                        "(%s items). Consider refreshing your cookies.",
+                        data["post_shortcode"], len(candidates))
+                elif image["width"] < item.get("original_width", 0) or \
+                        image["height"] < item.get("original_height", 0):
+                    self.log.warning(
+                        "%s: Available image resolutions lower than the "
+                        "original (%sx%s < %sx%s). "
+                        "Consider refreshing your cookies.",
+                        data["post_shortcode"],
+                        image["width"], image["height"],
+                        item.get("original_width", 0),
+                        item.get("original_height", 0))
+
             media = {
                 "num"        : num,
                 "date"       : text.parse_timestamp(item.get("taken_at") or