Now this is my kind of deck builder!
Alright, so my favorite card strategies are Timid, Greedy, and Polite. Greedy has those big plays, and Polite has a strong economy that makes me feel smart for making good decisions about when to play its card. Timid is an exceptionally satisfying and powerful strategy to use. It's very sneaky, and has a tendency to snowball and snatch victory in just a few turns if not managed by enemy Negates or Steals. One of the strongest playstyles I've found involves using Timid's "Unlock Potential" in conjunction with its "Hidden Eating" card to consume food and drink for triple its value at a discounted price. For instance, using this combo, you can discard "Big Soda" for +30% WG at a cost of only 3 Paw Coins (not counting the 6 you spent on "Unlock Potential"). With an aggregate cost of 9 Paw Coins for 30% WG compared to the ratio of 8 PC : 20% WG for "Burger Overdose" I would even go as far as to suggest raising the cost of "Unlock Potential" slightly.
Okay, so check it, Tricky could use a little help. "Infinite Drink", while making food access more consistent from the hand, does not have a high enough +%WG to be worth adding to the deck currently. "Food Duplication" and "Card Steal" both also cost a little too much, but that's just my opinion. "W.G. Pill" is great and practically makes up for all of the lackluster cards in the strategy.
On the subject of suggestions, it may be worth checking the wording of some cards in order to alleviate confusion. More specificity would help. As an example, cards like "W.G. Pill" and "Food Duplication" both refer to the 'next' or 'previous' card played and mean different things ("W.G. Pill" refers to the next card you play, while "Food Duplication" refers to the previous card played in the chain).
Please continue to expand on this game-- you've got a really neat idea for this project and much of the framework right now is solid!
( as a sidebar: it would be a fun~ alternate sort of game mode where instead of both players trying to fatten up their own character, they try to drive their opponents weight up to maximum first instead... it is called "feed battle" after all... ;> )