Twenty-four-hour serum TSH concentration time series in 24 healthy men and 22 healthy women. Blood samples were taken every 10 minutes for 24 hours. Blood sampling started at 9AM. Lights were off between 11PMand 7:30AM. Data are shown as the group mean and SEM. [Reproduced from F. Roelfsema et al: Thyrotropin secretion profiles are not different in men and women.J Clin Endocrinol Metab. 2009.

Low TSH and osteoporosis.

Prolonged fasting diminishes thyroid-stimulating hormone (TSH) secretion by reducing burst amplitude and by blunting the nocturnal increase. It is recognized that TSH plays a role in maintaining bone health. If following a restrictive diet results in the suppression of the nocturnal rise in TSH and diminished burst of the hormone, it may be detrimental to bone health.

Minnesota starvation experiment.

The heart was consistently and markedly reduced in size by the starvation. While the measurements are not completed it appears that the total heart size shrank more than in proportion to the body weight, perhaps as much as the calculated “tissue” change mentioned above (41%).

Caloric restriction (CR) for weight loss: “10% CR” and “30% CR”, both high carb, produced similar weight loss.

The diets were hardly optimally designed for weight loss. Still, the subjects lost 8% of their body mass by the end of the 12-month study period.
The subjects on the diet with higher carbs (60% of the caloric intake) were somewhat more stressed by the reduction in calories than the subjects on lower (40% of the caloric intake).
The good outcome was that there was no profound reduction in the metabolic rate of the subjects.

A Schematic Overview of Causes and Consequences of PEW. *Although PEW is strongly associated with these adverse events, the degree, if any, to which PEW actually causes these adverse events is not known (see text). CVD, cardiovascular disease; DM, diabetes mellitus; HF, heart failure; IGF-I, insulin-like growth hormone-I; PEW, protein-energy wasting; PTH, parathyroid hormone.

Protein-energy wasting (PEW).

During our review of literature on the effects of prolonged (unintended) caloric restriction, we came across an interesting article on protein-energy wasting (PEW) by Lodebo et al., 2018 (1).

Valter Longo’s “FMD” in humans and mice in perspective: mice lose 15% of body weight in 4 days of FMD.

In mice, organs return to the previous size after several days of refeeding. This does not seem to be true in humans.

This may be why you feel lethargic: “spontaneous physical activity” dropped by almost a half after prolonged dietary restriction.

Below, there is a table from a study published in the year 2000 by Weyer, Walford and colleagues. The study described human metabolism during and after 24 months of (unintended) caloric restriction experiment in the “Biosphere-2” confinement.

Valter Longo is catastrophically wrong during a Ted Talk in 2016 when he says that the organs of the emanciated man shrank by 50 and then grew back to normal size. In reality, no gain of lean mass occurred during the six months of the refeeding period. Longo did not read the paper attentively or forgot what was inside.

Debunking Valter Longo: What happens to human organs during caloric restriction or fasting?

Valter Longo often cites the seminal paper of his mentor Walford on prolonged caloric restriction. However, it appears that Longo either did not read the paper or does not remember what the paper says.