Dr. Eric Berg, DC

Berg's work adds a second hormone to the insulin story: cortisol. He teaches that chronic stress keeps cortisol elevated, and that elevated cortisol can make insulin resistance worse, which is why he teaches ketogenic eating and fasting together rather than as separate tools. On his view, lowering insulin through food choices does less if cortisol is working against it at the same time, and Berg's frameworks are built to address both.

The other piece of Berg's teaching is nutrient density. He has long argued that electrolyte and micronutrient shortfalls, not just insulin, undermine energy and fat loss, especially for anyone changing how they eat. RealFoods cites his published work among its sources on insulin and body fat. Berg has not reviewed or endorsed the app or the Weight Impact Score.

The Healthy Keto Plan combines his ketogenic and fasting recommendations into one practical protocol aimed at regulating insulin and helping the body adapt to burning fat for fuel. The RealFoods fasting pages below explain how eating windows work in general terms.

Berg has built his following specifically around weight loss without calorie counting. Rather than asking people to track totals, his content walks through which foods and habits he says move insulin and cortisol in the right direction. That practical, video-first teaching style has reached an unusually large audience for metabolic health content, and much of it distills down to a short list of levers: what to eat, when to eat it, and how to manage stress so cortisol does not undo the insulin benefits of the first two. His emphasis on nutrient deficiency is a recurring theme too: a food that looks good on hormonal impact should still be nutrient dense, not just low in whatever a person happens to be avoiding that week.