&gt;Diets often do improve cholesterol, blood sugar and other health markers in the short term, but these gains may result from changes in behavior like exercising and eating more vegetables<p>um, &quot;changed in behavior ... eating more vegetables&quot; -aka- &quot;diet&quot;.  So in other words &quot;fad and crash diets&quot; don&#x27;t work.  But &quot;improving your diet&quot; does and always has.