On your keto food list, stick to low-glycemic sweeteners to avoid spikes in blood sugar, and avoid fillers and binders such as maltodextrin and dextrose, which can spike blood sugar and contain sneaky carbs. Sugar alcohols such as maltitol or xylitol may read as no sugar on a label, but be aware that they will still cause moderate glycemic response when digested.
It sounds like you have used ground/mince beef that was too fatty and the fat has rendered out into the casserole. I tend to avoid low fat beef as we want plenty of healthy fat to keep us fuller for longer and all the benefits that come from a high fat diet, but I also avoid the highest fat beef as too much fat comes out in the cooking process for a dish such as this one.
The benefits above are the most common ones. But there are others that are potentially even more surprising and – at least for some people – life changing. Did you know that a keto diet can help treat high blood pressure, may result in less acne, may help control migraine, might help with certain mental health issues and could have a few other potential benefits?