Fat substitutes and low-calorie fats: A compile of their chemical, nutritional, metabolic and functional properties

Fat replacers are added to food to provide some or all of the functional properties of natural fat while providing fewer calories. The majority of fat-based replacers are either low-calorie fats that include chemically altered triglycerides or fat substitutes (i.e., lipid analogs that are neither hydrolyzed nor absorbed by the body as natural fat). This review capitalizes on fat substitutes of different origins in the context of their different chemical synthesis, lowering calorie mechanisms, nutritional benefits, metabolism, and safety reports of these substitutes in humans are dissected for the first time in relation to their metabolic byproducts inside humans. Besides, their functional properties and recent advances in pharma-food applications are reviewed. Fat substitutes offer a trendy replacer with less health risks compared to conventional fats. Their different structural chemical classes exert their low-calorie actions under different action mechanisms like emulsification or modification as structured lipids. Regarding their metabolism, they can retard the absorption of some nutrients acting as anti-nutrients, while their biotransformation products inside the colon might affect microbiota activity or predominance. Fat substitutes offer multiple functions in food processing, using them as preservatives and developing therapeutic tailor-made fat substitutes are the futuristic directions without their current side effects, especially if consumed regularly.