Nothing about your diet changed at 45.
What changed is what your body does with it.

Daily nutrition

What quietly changes for men after 45

Ask most men in their late forties what they eat and the answer is roughly what they ate at thirty. That's usually true. What isn't the same is how the body handles it — energy needs, protein requirements, and how efficiently certain nutrients get absorbed all drift over a decade or two, and none of it announces itself.

The four below are the ones that show up most often, and none of them require a diet. They're changes of order and timing.

• ✓ Protein It ends up stacked at dinner A typical day runs light on protein at breakfast and lunch, then loads most of it into one evening meal. Protein needs tend to rise with age, and spreading the same total across three meals is a change of order — not a change of diet.
• ✓ Fiber The weekly rotation narrows By this age most men are cycling through six or seven reliable meals. Convenience wins, variety drops, and fiber is usually the first thing to go — most adults already fall short of the daily recommendation.
• ✓ Timing The eating window drifts later Later dinners, a snack after it, and a first meal pushed back to mid-morning. The total may not change, but a compressed late window tends to sit badly with sleep, and poor sleep feeds back into appetite the next day.
• ✓ Portions They stay the same while activity doesn't Daily energy needs decline gradually with age, largely because people move less and carry less muscle. Serving sizes rarely follow. The gap is small on any given day and obvious over a few years.

None of this calls for an overhaul. What it usually calls for is deciding the shape of the day once — what breakfast looks like, when the last meal happens — so it stops being negotiated every morning.