The mantra "bigger is better" has been touted for centuries. In today's modern world, is bigger really better when it comes to food?

The notion that bigger is better is problematic in many respects; however, it is particularly problematic with regard to food. For one, industrial-sized farming operations incur tremendous environmental costs because they use large amounts of water and contribute to global warming. Industrial meat and dairy production, for example, has been implicated as one of the leading sources of CO2-emissions worldwide.  
Secondly, big portion sizes, especially of highly processed foods, have long been implicated as being a major contributor to the obesity epidemic. The Centers for Disease Control and Prevention (CDC) estimate that 36.5% of Americans are obese. This is a public health crisis because obesity is associated with a host of other diseases including heart disease, Type 2 diabetes and cancer. Apart from increased healthcare costs caused by treating obese patients, people also experience reduced quality of life due to these diseases.  
So overall, when it comes to food, bigger is definitively not always better.
https://www.cdc.gov/obesity/data/adult.html