Some papers by Varady et al., looking at fasting and blood lipids

It is interesting to compare them all, which I will try to do below.

The first in the list shows that on the ADF regime, it made no difference whether the subjects had a high fat or a "healthy" diet on feed days...they lost a similar amount of weight, fat mass, and waist circumference. LDL cholesterol and triglyceride concentrations were reduced. HDL cholesterol, blood pressure, and heart rate remained unchanged. The study was only for 8 weeks so I don't know that we can read much into the lack of change in the blood pressure etc.

The second 2 papers published at the end of last year looked at using meal replacements vs food in an 8-week intermittent fasting regime where the subjects fasted for one day a week (only 120 cals allowed!) and for the other 6 days had a calorie-restricted (80% of energy needs) diet. One group had liquid meal replacements for breakfast and lunch and a food-based dinner on their 6 days while the other group had a food-based diet for all 3 meals on their 6 days. They aimed to have approximately 240 kcal for breakfast, 240 kcal for lunch, and 400–600 kcal for dinner. The diets were relatively high carbohydrate: (i.e. <35% of kcal as fat; 50-60% of kcal as carbohydrates; <200 mg/d of dietary cholesterol; and 20–30 g/d of fibre). One of the papers reported that weight decreased more with the meal replacements (3.9 kg compared with 2.5 kg)as did fat mass (2.8 kg loss compared with 1.9 kg in the food based diet). Reductions in total and LDL cholesterol levels were greater with the meal replacements, while heart rate, glucose, and insulin, decreased the meal replacement group only. The other paper is, I think, using the same group of subjects as the first but reports on changes in various hormones including leptin, and insulin-like growth factor-1 (IGF-1) which decreased in the meal replacement group only.

In the discussion, the authors say that they think the differences in their findings is due to the fact that the meal-replacement group lost more weight than the food-based diet group.

So, the bottom line here is that once a week fasting when combined with calorie restriction can bring improvements in many factors that are known to increase the risk of cardiovascular disease. All these regimens resulted in health improvements though most of them were due to weight loss. Of course the potential benefits in protecting against cancer and Alzheimer's could not possibly be known with only 8 weeks of dieting. The 6:1 regime with the liquid meals did show drops in IGF-1 though so it seems likely that our 5:2 regimen would also do so.