What You Need to Know About Intermittent Fasting, Snacking and Insulin

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Ever heard of intermittent fasting? What about snacking? A lot of people wonder, if I am intermittent fasting can I snack? Or is snacking in general helpful to lose weight? Well - in order to discuss the role of snacks in weight management and metabolism, we need to first discuss the research on grazing and intermittent fasting for weight loss and insulin sensitivity. Here comes some science on your Monday morning!

Grazing versus Meals for Weight Loss and Insulin Sensitivity

Pop culture wisdom may tell you that eating 6 to 8 small meals daily will help you lose weight, but studies don’t bear this out.  Recent, well-controlled prospective studies in overweight or obese individuals have shown that increasing meal frequency provides no significant benefit to glucose regulation, insulin sensitivity, lipid profile or weight loss success provided the diet overall is well-structured to support weight loss. And, while increasing meal frequency may help protect against loss of lean muscle mass during weight loss, the effect is much smaller than the preservation of lean muscle mass afforded by eating a higher protein diet (say 30% calories from protein) during weight loss and by exercising—especially strength training—during weight loss.

On the flip side of the coin, however, there’s no benefit to reducing meal frequency either, despite the fact that feeding windows, time-restricted eating, and intermittent fasting have hit the weight loss world by storm. While these strategies can lead to a spontaneous calorie reduction, they come at an expense.  One study evaluating the effects of 1 meal per day showed that, despite modest fat loss and in body composition, subjects had increased total, LDL and HDL cholesterol.  Another study evaluating the effects of 1 meal per day showed decreased insulin sensitivity, elevated fasting glucose, and impaired morning glucose tolerance. Yet another study with a cross-over design that evaluated a reduced feeding window achieved by skipping breakfast showed that participants had higher postprandial glucose and insulin levels after lunch compared to days when the same participants ate breakfast. And over 6 weeks, participants who skipped breakfast experienced no weight loss benefit nor improvements to glycemic control, plasma lipids, or inflammatory markers compared with the control group. 

Collectively, these studies show us that there’s a benefit to eating breakfast (especially one that includes quality protein), and that eating something like 3 meals a day is probably optimal. But most importantly, the overall quality of the diet, total caloric intake, and lifestyle factors are much, much, much bigger influencers of weight, insulin sensitivity and metabolic health than how many time per day you eat and when.

So, what about snacking?

Snacks, Weight Loss and Insulin Sensitivity

Did our hunter-gatherer ancestors snack during the day?  The social construct of “the meal” was something that came with the advent of agriculture.  Prior to this, food was eaten shortly after it was hunted or gathered, adding fluctuation to food intake, varying day-to-day, and generally more frequent in times of feast, less frequent in times of famine. Also, women and children were more likely to “snack”, eating some foraged food as they were gathered.  This may have helped to promote growth in children and fertility in women.

This quote sums it up well:

“The view of the hunter-gatherer as a central place forager does not discount the likelihood that some fraction of foraged food was eaten at the time it was encountered (viz, snacking). This might have been especially true in children who were included in gathering from an early age—and some amount of snacking was likely to have been tolerated. The much more recent advent of agrarian societies has probably sharpened the rules of meal structure. The critical aspect of this argument is that meals are NOT an intrinsic biological property of H. sapiens, but are instead are a product of social and economic imperatives.”  Rowland NE. Behav Brain Res. 2012 Jun 1;231(2):272-8.

So, we can stop demonizing snacks as somehow contrary to hunter-gatherer behavior.  But, just because hunter-gatherers did it, doesn’t automatically mean it’s good for us.  So, what does contemporary science actually tell us about the pros and cons of snacking?

Studies are finally evaluating snack quality in addition to snacking behavior, and it turns out that this is of vital importance in determining whether there is a benefit or detriment to snacking.

In terms of behavior, “snacking” has a completely ambiguous impact on weight and health, with some studies showing that snacking helps maintain a healthy weight, others showing that snacking causes weight gain, some studies showing that snacking is associated with poor diet quality and yet others showing that snacking is associated with high diet quality.  Just as choosing whole foods, lots of vegetables and fruit, quality proteins, and striving for nutrient sufficiency are essential for a health promoting diet as a whole, the same can be said of individual meals and snacks.  Whether or not you snack is not a determinant of weight loss success or of health; instead, it matters what you snack on!  So, provided you’re choosing healthy foods to snack on, there’s absolutely no detriment to snacking itself.  And, in terms of weight loss, there may even be a benefit, provided you’re eating the right snack… which brings me to the benefits of a high-protein snack!

Benefits of a High-Protein Snack

A few studies have demonstrated the benefits of choosing a high-protein snack on weight and insulin sensitivity. A recent study of healthy women concluded that, compared to high-fat or high-carb snacks, eating high-protein snacks, even if lower in calories, improved appetite control, satiety, and reduced food intake at subsequent meals. A similar effect was seen in a separate study of healthy men (interestingly in this study, fiber-enriched snacks did not show the same reduction in subsequent food intake). Another study in type 2 diabetics showed that high-protein snacks results in fat mass loss, despite no change in total energy intake. And yet another study in healthy women showed that a high protein, high fiber snack not only reduced energy intake at the next meal but also reduced glucose and insulin responses over the whole day. Finally, in a primate study, a high-protein, high-fat snack improved glucose regulation and maintained insulin sensitivity (the controls that did not receive a snack progressed toward higher insulin during the study).

Taken together, these studies make a compelling case for choosing snack foods that include high quality protein.

My New Fave: Chomps

This seems like a great opportunity to mention my new favorite high-protein snack: Chomps Jerky Sticks.  Sure Chomps has been around for a long time, but it’s their two new AIP flavors (Italian Style and Sea Salt Beef) that have me hooked!  All of their jerky sticks are made with 100% grass-fed and grass-finished beef or venison, or 100% free-range antibiotic free turkey, contain 9-10 grams of protein per stick, and are free of all the icky things: added sugar, GMOs, gluten, dairy, soy, artificial preservatives or colorings, binders, fillers, MSG, nitrates/nitrites (except those naturally occurring in celery), etc.

So be mindful about what you are snacking on, but don't tell yourself that snacking is bad for you! It certainly has its benefits as the studies I have shared tell us. Everyone is different, find what works for YOU and stick to it!

Have a great week Warrior!