I recently overheard someone explaining that it was called Fat Tuesday because people would splurge just before Lent. It wasn't the appropriate place to explain that the "fat" in mardi gras is not fat as in obese but fat as in LARD.
In the 21st century we in the Western Church have reduced Lent to giving up something, and not eating meat or Friday. The name mardi gras reminds us that Lent historically had a much greater impact on daily living. Not only was meat forbidden throughout the entirety of Lent but all products from animals which would have included eggs and all dairy products. Mardi Gras was the last day cooking with eggs, milk or Lard which is why things like pancakes, and doughnuts are associated with this celebration.
Tomorrow we begin the three traditional practices of prayer, fasting, and alms-giving found in tomorrows gospel from Matthew 6. For those who want to do the absolute minimum, it is true that our law only requires fasting on Ash Wednesday and Good Friday, and abstinence from meat on Fridays. The law was not altered to suggest we do less but to allow each of us to behave as adults and chose an appropriate penance that fits us. For some people eating seafood as opposed to meat all during lent would be a pleasure, and in many parts of the modern world certain cuts of meat are the protein of the poor, and seafood is a luxury. The Second Vatican Council may have over-estimated the maturity of the average Christian, and those in charge of catechesis often did a poor job of explaining the changes.
This year let us be the adults the Church hoped we would be. Let each of us choose appropriate forms of prayer, fasting, and almsgiving that we can live throughout Lent, as our penance for the past, and our hope of on-going conversion.