"Buy low, sell high“ is useless advice.

"Cut the carbs" is actually good advice because it's a specific and actionable step you can take to improve your health.
So focus on building a strong foundation of good habits, and maybe one day you'll be able to afford to buy low and sell high. (Fingers crossed!)

Good Habit Creation and Maintenance
* Choose a specific habit.
* Make it easy.
* Be consistent.
* Track your progress.
* Reward yourself.
* Don't give up.

Bad Habit Elimination
* Identify your triggers.
* Avoid your triggers.
* Find a replacement behaviour.
* Make it difficult.
* Tell someone.
* Don't give up.

Book recommendation:
"Atomic habits" - James Clear