Very low fat diets

Last update: 29 May 2022

Between 01-01-2022 and 28-05-2022 I have experimented with variations on a very low fat (<=10% energy as fat), after ceasing a calorie-restricted diet and regaining weight. This is a summary of the results of my experiences.


There are three distinct subtypes of the diet that I’ve tried during the time:

  1. Regular very low fat diet (VLF), comprising primarily the very leanest meats, lean dairy and primarily starchy sources of carbohydrate.
  2. High protein very low fat diet (HPVLF), comprising an increased proportion of lean protein sources, and less carbohydrate.
  3. Potato-only diet with some seasonings (SPUD), taking part in a 4 week community trial run by the Time Mold Slime Mold blog1.

The common themes were:

  1. Lack of energy prescription, ie. ad libitum feeding.
  2. Fat percentage kept at or below 10% of dietary energy.


None of the variants had a substantial effect on my body weight, as compared to my earliest measurements – circa 98kg (as of February 2018, when on an unstructured diet of uncertain traits, though probably classifiable as mixed). That said, the diets were not fattening, and yielded a small reduction in mass. This is consistent with the literature on the subject2.

Waist circumference is markedly less than the only datapoint from that time, 101cm. It is unlikely that this is a simple measurement error, as I still possess trousers from that time which are markedly too large as of time of writing, even though I have regained almost all of the body mass.

Low fat diets appear inferior in measures of adiposity as compared to low carbohydrate, high protein diets I’ve tried, though not by much.

Mixed – mixed, ad-libitum diet; LCHP – low carbohydrate, high protein diet


Low fat diets reduced total, LDL and HDL cholesterol, while elevating triglicerides. Aside from the decrease in HDL-c, this is consistent with the literature on the subject3.

TC = LDL + HDL + Remnants

Blood pressure

While the VLF and HPVLF are unremarkable in this regard, during SPUD, systolic and diastolic pressure increased. Why this occurred, and whether this is related to the diet, is not clear.

Note that the pre-SPUD measurements are irregular, whereas during SPUD, the measurements were consistently performed in uniform circumstances and protocol every day.

Oral glucose tolerance and insulin response

VLF and SPUD offer improved results over a low carbohydrate, high protein (LCHP) diet, but that result cannot be considered “bad”, doubly so in light of earlier testing of LCHP showing better results than this one. Diabetic-like glucose intolerance is a known side-effect of carbohydrate-restricted diets4, but it’s questionable whether this signifies any harm.

Improved glucose-insulin dynamics are consistent with some older literature on the subject5.

Note: Fasting insulin for the LCHP test was flagged potentially erroneously low by the laboratory. Pattern refers to Kraft patterns6.

Iron, liver and thyroid panels

The results were not markedly different from results on other diet patterns I’ve tried.

Adverse effects

Flatulence was the major side-effect, particularly when the starch source happened to be tubers. Intestinal gas buildup was particularly bad during SPUD. This problem was much reduced, but not absent, if the starch source was low-fat grains.


  1. “Potato Diet Community Trial: Sign up Now, lol”, Time Mold Slime Mold, april 29, 2022.
  2. Hooper L, Abdelhamid A, Moore HJ, Douthwaite W, Skeaff CM, Summerbell CD. Effect of reducing total fat intake on body weight: systematic review and meta-analysis of randomised controlled trials and cohort studies. BMJ. 2012 Dec 6;345:e7666. doi: 10.1136/bmj.e7666. PMID: 23220130; PMCID: PMC3516671.
  3. Lichtenstein AH, Van Horn L. Very low fat diets. Circulation. 1998 Sep 1;98(9):935-9. doi: 10.1161/01.cir.98.9.935. Erratum in: Circulation 1998 Oct 27;98(17):1828. PMID: 9738652.
  4. Klara R Klein, Christopher P Walker, Amber L McFerren, Halie Huffman, Flavio Frohlich, John B Buse, Carbohydrate Intake Prior to Oral Glucose Tolerance Testing, Journal of the Endocrine Society, Volume 5, Issue 5, May 2021, bvab049,
  6. DiNicolantonio JJ, Bhutani J, OKeefe JH, Crofts C. Postprandial insulin assay as the earliest biomarker for diagnosing pre-diabetes, type 2 diabetes and increased cardiovascular risk. Open Heart. 2017;4(2):e000656. Published 2017 Nov 27. doi:10.1136/openhrt-2017-000656