New Concerns of Keto Causing Visceral Fat & Insulin Resistance - Dr. Sean O'Mara Explains

Thomas DeLauer first raises this point, noting that on low-carb, people could lose weight without much exercise, but on a high-sugar diet, you 'better dang well be moving' because sugar is an exogenous fuel. Dr. O'Mara strongly agrees, emphasizing that you must adopt 'maximum intensity working out.' He credits Mark Bell, a prominent sugar diet advocate, for doing this — adding sprints and high-intensity work to his routine. He also mentions Dr. Shawn Baker has adopted more sprinting. Both Thomas and Dr. O'Mara frame this as the critical difference between the diet's potential theoretical short-term benefits and long-term damage. Without the demand, the supply becomes lipogenic and glycating.

Dr. O'Mara has not yet seen anyone on the sugar diet publish MRI data. He's deeply concerned that while people may lose scale weight, they are losing the wrong kind of fat and possibly gaining visceral fat. He offers to share anonymized N-of-1 MRI data on his social media to help the community understand the structural consequences. This protocol is framed as a way to practice 'treat the patient, not the number' — with structural disease being the true endpoint.

Dr. O'Mara spent a significant portion of the conversation building the case that modern lab norms are meaningless for metabolically healthy people. He used the parallel of the LMHR (Lean Mass Hyper-responder) debate on cholesterol, where elevated LDL didn't translate to disease. He argues that the 'insulin resistance' seen on low-carb is a new physiological state, not pathology, and comparing it to diabetic insulin resistance is a category error. His mandate is to figure out what actually predicts disease — and for him, that's visceral fat, muscle fat, and loss of superficial subcutaneous fat plus functional decline. This protocol is essentially his entire clinical philosophy.

Thomas shares that his mother, a healthy person, would intuitively do a 1-2 day juice or fruit fast occasionally and then return to a meat-heavy diet. Dr. O'Mara remarks that this aligns with a natural episodic consumption pattern and contrasts it with the sustained sugar diet which he views as a fad. They both acknowledge that a short sugar fast may have benefits like FGF-21 elevation without the downside of chronic high carbohydrate intake.

Dr. O'Mara parallels this to the earlier fear over elevated LDL on keto, which later research showed didn't necessarily correlate with disease. He argues that the insulin resistance label is being applied to people who have simply shifted their fuel preference. Just as lean mass hyper-responders have high cholesterol without harm, these individuals may have higher fasting insulin or glucose as a new physiological setpoint, not disease. He sees the sugar diet as a knee-jerk reaction to a number, reminding listeners that average reference ranges are built from a profoundly diseased modern population. He is actively collecting data on what happens structurally to sugar dieters and plans to file intellectual property on his observations, though he cannot disclose details yet to preserve patentability. The implication is that the sugar diet is a fad that, if sustained, may cause underappreciated harm, including glycation and shifts in fat distribution.

Dr. O'Mara explains that superficial subcutaneous fat is not the same as the 'stubborn belly fat' people want to lose. It's a very thin, healthy layer that produces adiponectin, a molecule protective against heart disease, diabetes, neurodegeneration, and multiple cancers. Infants and healthy children have abundant superficial subcutaneous fat; the elderly lose it and are burdened with more disease. He worries that the sugar diet is shrinking this beneficial fat depot while possibly increasing visceral fat and muscle fat. He has seen this pattern in dieters and urges anyone on the diet to track via MRI. He notes that the enthusiasm for the diet is understandable but that the glycation from high sugar intake is also being underappreciated.

Dr. O'Mara brings up glycation as a primary concern he has with the sugar diet, noting that adding large amounts of carbohydrates, especially simple ones, will dramatically enhance AGE formation. He contrasts this with the relative safety of low-carb where glycation is minimized. He doesn't provide a long exposition on AGEs, but it's a clear warning flag he raises alongside the structural fat concerns.

Thomas argues that the same adaptability argument used against keto can be applied symmetrically. If a person drastically reduces fat intake for a long period, the body may downregulate fat oxidation pathways, leading to lipid intolerance — an inability to properly process fats upon reintroduction. He suggests that accumulated lipids in the blood could be far more harmful than glucose, because the body can dispose of glucose more easily (e.g. via urine in extreme cases), whereas lipid accumulation can lead to vascular damage. Dr. O'Mara agrees and notes that no studies have properly examined this, but it's a valid theoretical risk that should be considered.

Dr. O'Mara notes that fruitarians are often idealized online, but those he has studied present a disturbing picture: nearly no fat, gaunt faces from loss of subcutaneous fat, profound muscle wasting (sarcopenia), and accumulation of various diseases before premature death. He sees the sugar diet as following this same underlying macronutrient pattern — primarily carbohydrate, little fat or protein — and predicts similar consequences over time. He explicitly states that the sugar diet reminds him very much of fruitarians, and worries that people will see a decline in performance and health if they sustain it.