|I wonder if she just found out that sheddin 10% body fat can be as easy as doing two "protein modified fasts" per week!?|
Still, the latest study from the University Hospital of South Manchester NHS Foundation Trust comes with a couple of very interesting results... the only downside is that the subjects were "the usual" ones, namely obese sick people: 115 women with a family history of breast cancer (aged 20 and 69 years). This is problematic, because the same fast during which the obese person draws on his or her fat stores to "survive" can sent the lean sub 10% body fat athlete into a catabolic low energy state and have his blood sugar drop to hypoglycemic levels, when he or she returns to eating ad libitum after the 2 fasting days.
Will intermittent fasting shrink your bust?
Sorry, I just could not resist to use focus on this question of paramount importance. Why? Well the study at hand is the first to actually investigate the negative effects of fasting on your cup size ;-) All jokes aside, this is obviously not a non-sense or cosmetic measure.
As I already mentioned in the introduction, the subjects had a history of breast cancer and in view of the association between breast cancer risk and bra cup size in US women aged <42 (Swanson. 1996) -
- 26% increased risk for cup size B
- 23% increased risk for cup size C
- 95% increased risk for cup size D*
|Figure 1: Change in body composition in response to dietary energy restriction (-25%; DER) and 2-day per week fasting with calorie (IFC) and carbohydrate (IFCA) restriction on the two fasting days (Harvie. 2013)|
Details on the protocol: Diet composition
Side effects? What is interesting and something I have not seen before in a study is an evaluation of differences in side effects and nutrient sufficiency:The dietary energy restriction (DER) and the intermittent fasting carbohydrate restricted (IFC) groups were isocaloric and contained only 75% of the calculated energy requirements of the women. Contrary to the women in the DER group who consumed a diet with a macronutrient ratio of 25/45/30% protein / carb / fat, the subjects in the IFC group were however
- feeling cold (3% DER)
- decreased energy (5% IFC & DER)
- constipation (8% IFC, 3% DER)
- headaches (5% IFC, 3% IFCA)
- bad breath (5% IFC, 3% IFCA)
- light-headed (3% IFC)
- lack of concentration (3% DER)
- mood swings (3% IFC & DER)
- thinking about food 24/7 (8% IFC, 3% IFCA & DER)
Of the usual low-carb diet deficiencies in Mg, Fe, Zn, Ca, vitamins A and D and fibre, the multi compensated everything but the scarcity of magnesium (Mg), zinc (Zn) and selenium (Se) in the IFC group.
"asked to restrict energy and carbohydrate on two consecutive days each week (70 % energy restriction and 40 g carbohydrate) and to consume a euenergetic Mediterranean-type diet that met their estimated energy requirements for the remaining 5 d of the week."The restricted IFC diet the subjects consumed on those "fasting days" provided between 625kcal/day and 680kcal/day and included approximately
- 250 g of protein foods including lean meat, fish, eggs, tofu, textured vegetable protein,
- three servings of low-fat dairy foods (e.g. 195 ml semi skimmed milk, 150 g low-fat yoghurt, 30 g low-fat cheese),
- four portions of low-carbohydrate vegetables and
- one portion of low-carbohydrate fruit,
- at least 1170 ml of other low-energy fluids, and
- an over-the-counter multivitamin and mineral supplement providing the RDA for vitamins and typically 20 – 50 % for minerals on restricted days.