At 5' 11" and 175 anyone is very close to potentially having a six pack. We all know how to lose body fat - cut out everything that we know contributes to it.
If I wanted a six pack again I'd basically go vegetarian for few months...all the while walking uphill and doing a variety of ab work everyday because the abs are muscles of endurance and we can work them every day....along with resistance training because lean muscle will burn fat while we sleep.
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In my prime (30 - 40) I was 5' 10" and 145 lbs. and had a Bruce Lee body (damn near), played tournament USTA tennis and worked out at a club 4 times/week.
I had a wicked six pack that would only be noticeable if I shaved my belly hair.
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I worked out along side of those who competed in local and state body building events. What they did two weeks prior to an event was to eat only Tuna fish packed in spring water and steamed Broccoli - nothing else - so that their skin would hug their body so tightly that their muscles would "jump out".
Most would not drink water a few of days prior...but suck on ice.
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Barring some affliction/disease, I'd say that having a six pack at middle age is possible, it's just not painless.
Remember, it's a process and not an event.
So there ya go.
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PS These days I'm 190 - 195 and I look like a slob.
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