Intermittent Fasting: Diet Craze or Letigimate Science?

Call it Intermittent Fasting (IF), alternate day fasting, 5:2 Diet, 4:3 Diet, 18-hour Diet, Every Other Day Diet, Fast Diet or Starvation Diet, but going without food for a period of time each week continues to gain attention in the scientific community. Classic animal studies linking calorie restriction to longevity have suggested protection against obesity, type 2 diabetes, inflammation, hypertension, cardiovascular disease and reduced metabolic risk factors associated with cancer while improving markers of cardiovascular aging (1). Long-term daily caloric restriction is difficult to maintain in humans as it often induces weight re-gain and non-compliance. Is intermittent fasting any easier or more effective than eating fewer calories on a daily basis? I decided to find out for myself.

Here’s why people are talking about fasting:

An article featured in the Wall Street Journal this past December highlighted some benefits of IF stating: “Fewer Americans are dieting but they still want to shed pounds” (2). Weight loss aside, from a clinical standpoint, why diet if you won’t experience added health benefits? This article explored the possibility that fasting improves Alzheimer’s symptoms and cognitive function as well as the ability to maintain muscle mass with aging (3). IF also appears quite effective regarding weight loss with some of the most relevant information coming out of our very own University of Illinois Chicago focusing on alternate day fasting (4,5).

There are many theories on how IF works for both cognitive and cardiovascular improvements and weight loss. Fasting may induce a state of stress on the body causing the brain to release proteins that help stimulate the growth of neurons. It may reduce the rate of destruction of telomeres (caps at the end of chromosomes) by inducing less oxidative stress than eating every day (6). Traditional daily caloric restriction can slow metabolism rate, but eating normally most days of the week with fasting two-three days may not have the same effect (7). The body will not use fat stores when glucose is available in the blood, muscles or liver but during fasting when glucose is not readily available, fat will be used for fuel instead. In the fed state, the storage hormone insulin increases fat storage as it decreases blood glucose so without it, glucagon takes over promoting gluconeogenesis and glycogenolysis. One older human study on intermittent fasting from 1998 on overweight or obese women compared either daily caloric restriction or fasting for two days per week for six months. The study showed greater weight loss and reduction in fasting insulin and insulin resistance with IF with equal improvements in leptin, free androgen index, high-sensitivity C-reactive protein, total and LDL cholesterol, triglycerides, blood pressure and increases in sex hormone binding globulin, IGF binding proteins 1 and 2 (8). A more recent human study from 2011 proved similar results suggesting that intermittent fasting in a human population may produce many health benefits beyond losing extra weight (9).

Compelled by the potential health benefits of IF, I wanted to give it a try to see how I felt as a test before I would even mention it to patients. Fasting is not something I ever thought would be possible; I like eating often and I have a strong appetite. Here’s a brief record of my first few weeks fasting two days and eating five:

Day 1: I was planning on fasting on Mondays and Thursdays but since I had no plans this Friday, I decided to start before the weekend came. I had dinner around 7pm Thursday night and was planning on consuming only the recommended 500 calories until breakfast on Saturday. Drinking coffee on the way to work, I felt the urge to eat (my regular routine!) but when I paid more attention to how I was actually feeling, I wasn’t really hungry, so I waited. The morning was busy with patients and I was surprised at how clear-headed I felt. At noon, I had a plate of salad greens with some steamed broccoli on the side, two ounces of chicken breast and a few pieces of melon. Feeling fine, I finished my day and had a grapefruit around 4pm before heading home. I went to yoga, though I feared feeling weak or tired, and had one of the best classes in recent history! I felt energetic and well balanced and even accomplished a head stand. Back at home, I had brown rice, two cups of veggies and some tofu and hit my 500 calories for the day. The evening was much more difficult than earlier in the day as I dealt with a flooded basement, pushing bedtime back further than anticipated. I decided to have a banana late in the evening as I was feeling overly hungry. Call it 600 calories, my first day was a success.

Day 2: I was definitely ready to eat in the morning, but did not have the urge to eat any more than usual. A latte and egg white wrap were all I needed with tacos for lunch and a dinner out. I do fear overeating on my “eating” days, but this first day seemed normal.

Day 4: Ready for fasting again, I drank coffee through most of the morning and again had a large plate of greens with two ounces of salmon and an orange for lunch. An egg and grapefruit got me through the evening and on my way home. We decided to stop for groceries later on and I was feeling so ravenous that I needed to grab something to eat right away when we were there – being surrounded by food at the end of a day of fasting is no fun. Having less than 200 calories left, I stood in the protein bar aisle and read labels until I found one with 190 calories. The evenings have been difficult because of the lack of structure and disruption to my routine. I typically spend several hours at night preparing food and cooking so having that time free has been unexpectedly hard.

Day 5: Eating normally throughout the day, I tried to keep it a little lighter because I was going out to Frontera Grill that evening. We had such a wonderful time at dinner and the food was great but I got so uncomfortably full that my stomach hurt. This is very unusual. Two people I am trying IF with have also noticed that when eating normally, they get fuller more quickly. It might be time to consider cutting down on portions during non-fasting days?

Day 7: Today was much more difficult than previous fasting days. I felt hungry as soon as I woke up. I was so busy at work that I was light-headed and feeling “out of it” by 1pm so I had some salad greens with an egg and some fruit. I had a grapefruit later in the day but felt low energy and hungry. I tried a new meal in the evening: Amy’s Light&Lean pasta and veggie bowl. Strangely, I’m being drawn to these types of convenience foods when I’m fasting. They’re easy, I know how many calories are in them and they are perfectly portioned. I eat more fruit than usual on fasting days as well.

Day 8: I lost two pounds one week into my IF adventure. My co-worker lost 1.5. For more seriously weight loss (which was not our main goal anyhow), I think alternate day fasting would be more effective. Research shows this as well. 5:2 is challenging enough for me right now, so I’ll stick with it for my goal of three months and see what happens.

Day 11: This day of fasting was much easier than the last. Mondays seem easier than Thursdays in general. Drinking coffee and water throughout the day is helpful. Greens and protein are my go-to lunch with a piece of fruit in the early evening. The evenings and nights continue proving most difficult, but it’s hard to tell whether it is actually the fasting or this terrible negative degree weather making me feel down. I wonder if it will be easier when it’s warmer out and I can go outside for a walk instead of sitting in the house on a fasting night.

Day 14: Thursday was more difficult again, especially in the evening but it is crazy how normal fasting is starting to feel. I felt more anxious about it when I first started and it was harder to get through the day. When I go grocery shopping now, I take fasting days into account and pick up things I know I’ll need: low calorie frozen meals, salad greens and veggies, protein bars relative low in calories but high in protein, eggs to hard boil, fresh fruit, unsweetened almond milk for my coffee.

Day 15: Focusing on eating normally as I recently read folks were binging on their non-fasting days and with only two fasting days per week, you could easily overdo it on the other five days. I am noticing that I get fuller more quickly and am becoming better in-tune with

Conclusion: some studies claim that it takes about 30 days to adjust to IF. I can see barriers in the future on vacation or during a brief illness or stressful time in life potentially. At worst, IF is somewhat uncomfortable and can be socially isolating at times, at best it saves time, money, leads to greater fat loss than traditional dieting and could provide cognitive or cardiovascular benefits. My goal is to continue for a total of three months then re-assess to see if it may become a permanent lifestyle change in my routine. Overall, it has been a positive experiment and has not disrupted my daily routine much at all.

1. Is there anyone who should not try this diet?
Yes!! Anyone pregnant or who may become pregnant should not try this diet. Anyone who struggles with blood sugar issues (diabetes, hypo-glycemia) should not try this diet unless under strict medical supervision taking all medications into account. Anyone with a history or present eating disorder or disordered eating patterns should not try this diet as it can be quite restrictive. Medications should be assessed before starting a fasting diet.

2. On “eating” days, can you really eat whatever you want?
You are supposed to eat normally for the most part on non-fasting days, so sticking to your usual routine is best. Binging on junk food is totally counterproductive so try to stay reasonable. Especially on a 5:2 vs. alternate day, you run the risk of gaining weight if you overeat the majority of the time (5).

3. On “fasting” days, can you just chow on celery or other low-cal foods the whole day?
Sneaking in a large volume of low-calorie food where you are eating all day defeats the purpose of fasting. You are trying to give your digestive system a break and burn fat through depleted glycogen stores. Some IF diets only eat 500 calories once per day, but I find it easier to eat small amounts equaling 500 calories 2-3 times per day at regular meal times.

4. On “fasting” days, are you really hungry all the time?
I’ve read that it takes about a month to get used to this diet and I believe that is correct. I’ve had one really rough day but they seem to be getting increasingly easier. In some ways I like saving money and time by not cooking a couple nights per week and putting my energy into other ventures instead. There are definitely benefits and negatives to this diet, but I can see how it could be difficult with social situations, i.e. going out to dinner with friends but not eating, vacations or holidays.

References:
1. Cava E, Fontana L. Will Calorie Restriction Work in Humans? Aging. 2013 Jul;5(7):507-14.
2. http://www.advisory.com/Daily-Briefing/2013/12/04/The-latest-quick-fix-to-drop-pounds-Fast-twice-a-week
3. http://www.nia.nih.gov/health/publication/can-we-prevent-aging
4. Monica C Klempel, Cynthia M Kroeger, Surabhi Bhutani, John F Trepanowski and Krista A Varady.
Intermittent fasting combined with calorie restriction is effective for weight loss and cardio-protection
in obese women. Nut J. 2012 11:98.
5. http://www.theatlantic.com/health/archive/2014/01/the-new-way-to-love-food/283276/
6. Gilca M, Stoian I, Atanasiu V, Virgolici B. The Oxidative Hypothesis of Senescence. JPGM 2007, 53(3):
207-213.
7. Martin CK et al. Effect of Calorie Restriction on Resting Metabolic Rate and Spontaneous Physical
Activity. Obesity 2007, 15(12): 2964-73.
8. Williams KV, Mullen ML, Kelley DE, Wing RR: The effect of short periods of caloric restriction on weight
loss and glycemic control in type 2 diabetes. Diabetes Care 1998, 21(1):2-8
9. Harvie MN, Pegington M, Mattson MP, Frystyk J, Dillon B, Evans G, et al.: The effects of intermittent or
continuous energy restriction on weight loss and metabolic disease risk markers: a randomized trial in
young overweight women. Int J Obes 2011, 35(5):714-727.