Ask a researcher: Is the 5:2 diet healthy for women?

by @NTNUhealth 17 June 2014


Is the 5:2 diet healthy for women?


Answer from Catia Martins Catia Martins. Photo: Geir Mogen




5:2 diet is a type of intermittent fasting, which involves a “feed day”, where food is consumed ad libitum over a 24-hours period, alternated with a “fast day” where food intake is completely or partially restricted over 24 hours. The fasting days usually vary between 2-4 days/week.

Human studies have shown that intermittent energy restriction is as effective as isocaloric (meaning same energy content) continuous energy restriction (the conventional diet with daily energy restriction), regarding weight loss and reduction in obesity related risk factors (insulin levels, blood lipids and blood pressure).

A few studies have shown that intermittent energy restriction is associated with a lower loss of muscle mass and a lower reduction in resting metabolic rate compared with conventional diet. Some, but not all studies, show that intermittent energy restriction may increase adherence to the intervention as it would be easier to diet only some days of the week, instead of everyday, but long term studies are needed to be able to draw solid conclusions in this respect.


What about eating five days a week, and two days of fasting? (Photo: iStockPhoto).

Intermittent energy restriction seems to be safe, but mild side effects have been reported by some individuals; including fatigue, headache and lack of energy. However these are the same side effects expected with continuous energy restriction. Opposite to the general believe, intermittent energy restriction does not seem to lead to overeating (gorging) on the feed days.

The big challenge in the management of obesity is not weight loss, but the maintenance of a reduced body weight. Larger and long-term studies are needed to determine the ability of this novel diet to promote sustained weight loss in the long-term.

Overall, the available evidence from the few human trials available suggests that intermittent fasting can be used as an alternative to weight loss.

There is not enough evidence to say if 5:2 diet works differently in men compared with women

There is not enough evidence to say if 5:2 diet works differently in men compared with women. From my knowledge, no study has addressed specifically gender issues regarding intermittent fasting.

Regarding your questions if 5:2 is more or less healthy in women… well compared with what? With the conventional continuous energy restriction? 5:2 diet can, as explained, lead to a similar weight loss and improvement in risk factors as convention continuous energy restriction. A 5:2 diet can be nutritionally balanced if the diet during the 2 days of partial fasting is planned correctly so that no vitamins or minerals are deficient. One way to avoid that would be to use a vitamin and mineral supplement, another to use commercial available products which provide all the macro and micro nutrients in the right amounts (such as a very low calorie diet).

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