#162 - Sarah Hallberg, D.O., M.S.: Treating metabolic disease, & a personal journey through cancer

KEYPOINTS

• 01

  Carbohydrate restriction changed how Hallberg treated diabetes

  For the first half of more than 25 years in obesity care, Hallberg, trained in exercise physiology, prescribed low-calorie, low-fat diets, the dogma of the 1980s. Patients with type 2 diabetes kept progressing on insulin and insulin-raising drugs. Cutting carbohydrates let many lower or stop medication. That eventually led her to Virta Health, which treats type 2 diabetes remotely with continuous support toward nutritional ketosis.

• 02

  Most American adults are already on the path to metabolic disease

  About 10% of the US population has type 2 diabetes, and the rate is well into the teens in Hispanic, African-American and Pacific Islander populations. Recent studies suggest over 50% of adults have prediabetes or metabolic syndrome. Prediabetes means an HbA1c of 5.7–6.4%.

• 03

  Even 'normal' cut-offs are too loose

  Hallberg's practice targets blood pressure under 120/80 (the CDC cut-off is under 130/80) and triglycerides under 100 mg/dL rather than under 150. Fasting glucose under 100, HDL above 40 (men) or 50 (women), and a waist under 40 inches (men) or 36 (women) round out the usual definition of metabolic health.

• 04

  Triglycerides on a lab report mostly reflect VLDL

  Peter explains that most of a reported triglyceride level is carried in VLDL particles. In his example panel, triglycerides of 150 mg/dL go with a VLDL cholesterol of about 25, and he says most of those triglycerides sit inside VLDL, with some in intermediate-density lipoprotein. High triglycerides mean the liver is exporting a lot of fat.

• 05

  Dietary fat and blood fat are not the same thing

  In a feeding study, participants started under 50 g of carbohydrate a day and had carbs raised every three weeks across six phases, up to 346 g. Saturated fat intake fell from about 84 g to 32 g. Yet blood levels of certain fatty acids, especially palmitoleic acid, rose as carbohydrates went up. You are not simply 'what you eat'.

• 06

  Palmitoleic acid (16:1) is an early warning sign

  The liver turns excess carbohydrate into palmitic acid (16:0), and the enzyme SCD1 converts that to palmitoleic acid. Fructose via GLUT5, glucose via GLUT2 and insulin all push this pathway. Peter suggests it may be the liver protecting itself in the short term. Rising palmitoleic acid signals that carbohydrate intake is exceeding the person's tolerance.

• 07

  HbA1c flags trouble 10–20 years late

  Nobody 'rings the bell' until HbA1c passes 6.5%, often a decade or two after molecular warning signs appear. Hallberg cites studies linking palmitoleic acid in childhood (the PANIC study) to later health, and a Dutch study linking levels at 50 to C-reactive protein at 70. Data in non-white populations are lacking, since most studies enrolled middle-class white participants.

• 08

  Treatment should be individualized and early

  Hallberg says the only data that matter in the room are the patient's own. She also stresses that insulin is not benign: someone controlling glucose on 100 units a day is in a very different state from someone needing 20. Catching people earlier may mean they don't have to stay very low-carb forever.

• 09

  Lung cancer in never-smokers is common and often driven by specific mutations

  On June 30, 2017, at 46, a fit and health-focused never-smoker, Hallberg was diagnosed with stage IV lung cancer. About 12–14% of lung cancers occur in non-smokers, often EGFR- or ALK-driven. She has an EGFR exon 19 mutation. Median survival for stage IV lung cancer is often 12 months or less, though it depends heavily on the type.