&gt; You seem to be asserting that their issues with calorie restriction were lack of body fat.<p>No I&#x27;m asserting that what happens to people&#x27;s bodies at 4% body fat when in severe caloric restriction is <i>very</i> different than what happens to people&#x27;s bodies at 40% body fat with severe caloric restriction, and so we can&#x27;t apply the metabolic damage&#x2F;starvation models to fat people.  Fat people just need to eat less, and the issue basically comes down to compliance.  How do we get people to stay on a healthy diet long term?<p>&gt; do fat people get hungry? If they do, why?<p>Because, as even you have shown, hunger is not a reflection of your bodies actual caloric needs, it&#x27;s hugely a reflection of blood sugar levels, among other htings.  Given enough time (in the order of magnitude of minutes to hours) in an obese but otherwise healthy person fats will be broken down and blood glucose will increase and hunger will decrease.  It&#x27;s getting through that period that is a <i>mental compliance</i> issue, but not otherwise physiologically challenging.<p>&gt; The failure rate is astronomical<p>Again, this is a compliance issue.  People absolutely lose weight on caloric restriction, and starvation issues like low metabolism do not become an issue until you are very low body fat.  You simply do not see obese people going into so-called &quot;starvation mode.&quot;  In fact there are a few cases, though admittedly not many, of obese people that abstain entirely from eating for months at a time without long term &quot;metabolic damage.&quot;<p>&gt;  People can totally abstain from food for very long periods of time (depending on body fat), with very little hunger.<p>I think we basically agree, then, that it&#x27;s mostly a compliance issue and not an issue of caloric restriction working or not, and also that hunger is not a reflection of the body&#x27;s actual metabolic state (especially in obese people).<p>&gt; Fat people can get energy from fat stores, just not in the way we are typically told.<p>Fat people get energy from fat stores in the same way skinny people do.  Very skinny people on severe caloric restriction are not a good model for the general population.