lmao he was drinking from an IV fluid bag on page 9
Look up "weider in jelly", it's an energy-and-nutrient drink of sorts. He was also eating "calorie mate" bars in that frame.
Actual branding not depicted of course, but you can see the similarities in the shape of the packaging.
These sorts of products are stereotypical energy/nutritional supplement foods that workaholics are often shown eating in lieu of normal meals since they're compact, don't require cooking, don't create a mess or require significant cleanup, and are quick to eat.