Mostly based on this Healthline article + personal experience.

Calorie density of a specific food := calories per 100g. I have used this phrase for years before reading it.

— CalDensity diet [diet based on calorie density] don’t restrict a particular type of macronutrient but it naturally requires portion control on high-density “heavy” foods

A CalDensity diet is simpler than keto diet, low-carb diet, low-fat diet etc.

— Water content improves calorie density.

• boiled potato, boiled rice, compared to bread, pastry, baked starch
• smoothie with ice

Fruits have high water content + high fiber

— high-density “heavy” food list

• nuts .. a healthy fat, but requires portion-control in a calDensity diet
• cakes

— fasting

Even though I follow calDensity, I still need intermittent fasting (postpone 1st and last meals). One without the other is ineffective.