Dunkelweiss Thin Ideas to Improve in keg?

Been brewing for 1 year, today, and so I tasted my first attempt at a dunkelweiss.  From a kit. It came out good, but tastes thin.  Final alc. was only about 4%.  It sat in primary for 2 weeks & secondary for 2 weeks.  Kegged for 2 weeks.  Any suggestion for improving the taste at this point (and also in the future)? Can I place something in the keg to help?  Thanks.

I am by no means an expert but I believe your grain bill, mash temp, the yeast you select, and more all contribute to ‘mouth feel’. For example oats contribute a smoothness, higher mash temps encourage less Beta Amylase conversation and thereby less fermentability, and yeast that attenuate less can contribute to a higher viscous beer.

Thank you.  I did everything “by the book” but I suspected the yeast from the beginning.  Used a dry, packaged yeast that came with the kit.  I suppose I should be using liquid yeast for better results.

I disagree. I use dry yeast exclusively and do not suffer from thin beer.  What yeast did you use?

The dry yeast that came with the kit was Munich Ale Yeast (Danstar) for wheat beer.

Munich Classic is considered better but I have had good success with Munich. There could be other factors to consider

I wouldn’t try to fix it in the keg.  Take notes and fix it on the next brew.

I’m not sure how you would add body once it’s kegged.  If there’s a way, it likely oxidizes the beer and leads to premature staling…

Was this an all grain batch or extract?  If all grain, perhaps the wheat malt used was not ground finely enough leading to lack of potential sugars in your batch allowing for a lower starting gravity (hence only the 4% abv and subsequent thinner body)? 
I have experienced about a 10% decrease (in the past) in extract potential when using a significant portion (50-60%) of wheat malt in my beers. I have attributed it to not grinding my wheat enough.