The most straightforward way to restrict calories in the long term is to just continually undereat. It you don't overdo it, it will just make you weak and miserable, not dead.
However, it may not be necessary to actually do that. Intermittent fasting may give you the benefits of caloric restriction without actually starving you. Studies have shown alternate day calorie restriction (ADCR) to be quite effective, I'm not sure if there is hard data on other forms of (intermittent) fasting.
One possible mechanism as to why calorie restriction promotes longevity is that deficiency in essential amino acids triggers autophagy, a process by which cells recycle parts of themselves. Never being hungry may mean your body never cleans house, and crap like misfolded proteins just accumulate.
The easiest way to induce this may be to restrict protein temporarily. Try to temporarily get no more than 5% of you caloric intake from protein. Wheat as a protein-source is quite handy here, as it is low in protein to begin with, and especially low in lysine, so eating a little wheat will leave you deficient in lysine.
Tim Ferriss suggest a "protein cycling diet" as described by Ron Mignery in his book:
Protein restriction appears to take at 18 hours to trigger autophagy.