With a 500- to 600-calorie limit on your fasting days on the 5:2 Diet, you really do have to be judicious in what foods you're consuming. That's why the GI becomes especially important. Stick to foods and beverages that are high in protein and have low GI scores. You'll feel fuller longer and won't experience that dreaded sugar crash and empty-stomach feeling.
Some foods and beverages to stay away from on your fasting days include the following:
Typical high-carbohydrate foods, such as pizza, pasta, white rice, and bread: Not only are high-carbohydrate foods full of empty calories, but they also have high GI scores, meaning they wreak havoc on blood sugar levels. Sudden fluctuations in blood sugar levels will make fasting much more difficult and will negate fasting benefits, such as fat loss and increased insulin sensitivity.
Anything with refined or processed sugars in it (table sugar, high fructose corn syrup, agave nectar, and so on): As you are trying to avoid filling your caloric limits on your fasting days with empty calories, don't waste those 500 or 600 calories on simple sugars.
Even honey and maple syrup — two sweeteners that are better choices overall when it comes to satisfying your sweet tooth (but always in moderation) — should be nixed for the two days a week that you're fasting. If staying away from the sweet stuff is tough, just remember: It's only a couple times a week that you have to say no thanks.
Another added bonus to this is that giving up sugar a couple times a week will help you finally slay the sugar demon and break free of this highly addictive substance.
Be careful about adding sweeteners and such to your coffee. Although a cup of black coffee has a negligible five calories, a 16-ounce mocha has more than 260 calories — 330 calories if you add whipped cream.
Soda (regular or diet), sports drinks, or juices: Americans typically get 140 to 180 calories per day from sugary drinks, like soda and sports drinks. Avoid drinking the diet versions as well.
Alcohol: A 2012 study found that, on average, Americans consume 300 calories per day in alcoholic beverages. It may not seem like a lot, but consider how much it can add up to in a week. Besides, many people are consuming much more than that each day.
A 5-ounce glass of red wine has 125 calories. A regular 12-ounce beer contains more than 150 calories, and a double vodka and diet cola packs a whopping 258 calories. So imbibing in just one of these drinks can take a serious chunk out of the caloric limits on your fasting days.
Junk food, including chips, candy, pretzels, fruit snacks, buttery popcorn, and so on: One of the many benefits of fasting is the cleansing effect it has on the body. Consuming junk food, which is notoriously full of nutritionally subpar ingredients, on your fasting days will only put the toxins that you're trying to rid your body of back inside. Instead, stick to whole, natural, and preferably unpackaged foods during your fast days.