Now that a rough groundwork of what exactly Paleo is has been laid down, we're going to go ahead and examine some of the benefits of a Paleo-based diet in more detail.
Perhaps the most concerning and relevant point for the greatest number of people is how Paleo stacks up in terms of fat loss. If you think about it for a second, the food you'd be eating on a Paleolithic diet consists primarily of meat, vegetables, some nuts, and some fruit. You'll notice that means you'll be consuming quite a bit of protein, fairly low carbohydrates, and a lot of fat.
"But doesn't fat make you, well... fat? And won't eating a lot of fat raise my blood pressure, cholesterol, and generally make my heart explode?"
NO, and I intend to beat this point to death, revive it, and kill it again just for good measure.
This study, which is even more low carb and high fat than you'd typically experience with a Paleo diet concludes that "compared with a low-fat diet, a low-carbohydrate diet program had better participant retention and greater weight loss. During active weight loss, serum triglyceride levels decreased more and high-density lipoprotein cholesterol level increased more with the low-carbohydrate diet than with the low-fat diet."
Another study on weight loss showed "weight loss, fat loss, and percent weight loss as fat appeared to be inversely related to the level of carbohydrate in the isocaloric, isoprotein diets. No adequate explanation can be given for weight loss differences." Less carbs, more fat, more weight loss in this study.
In virtually every study I've seen, weight loss is greater and a higher percentage of weight loss comes from fat mass in diets that are lower in carbohydrates compared to lower in fat. There are many reasons behind this and I'll be grossly oversimplifying a few of them for brevity and clarity.
Insulin
Insulin is a hormone that plays a major role in nutrient storage. When your blood glucose (sugar) levels rise, which happens most dramatically with ingestion of carbohydrates, insulin is secreted and tells your body to store nutrients. Insulin acts not only on glucose, but also fats and protein. As such, spikes in insulin result in a storage of all of these different macronutrients and adding more to our fat stores is not what we're shooting for.
Glucagon
The counter-hormone to insulin which essentially prompts the release of glucose from the liver and free fatty acids from fat stores. Fat stores being utilized = good. One factor in the release of glucagon is decreased blood glucose, as high blood glucose and therefore higher levels of insulin inhibit it. We avoid spiking insulin by consuming carbohydrates primarily from vegetables, fruits with lower sugar content (berries, melons), and occasionally things like yams or sweet potatoes.
More satiation.
Intake of protein and fats generally leave individuals feeling fuller for longer, partly because blood glucose remains more stable and a whack of other hormonal factors (there's more going on when you eat than you think!). From here it's pretty simple: if you're more full for longer, you're probably going to eat less food. Less food means fewer calories, and provided you're eating enough calories for your activity level and metabolism, this is generally a good thing. However, under-eating is BAD and can sabotage weight loss just as much as over-eating can.
Fewer calorie-dense, low-nutrition foods.
Grains simply do not pack the same nutritional punch as other food groups and don't offer anything above and beyond what can be acquired from other edibles such as vegetables, meats, fruits, and nuts. On top of this, grains tend to have a high amount of calories per volume, which is primarily carbohydrates. A piece of bread is roughly 110-120 calories, comparable to 3 cups of broccoli at a caloric level. I don't know if you've ever tried to eat 3 cups of broccoli, but I promise you will be much more full than if you just had that slice of bread. On top of that, bread will produce a much greater spike in blood glucose and therefore insulin than the broccoli would.
Let's take a look at a typical Paleo dinner:
- Salmon fillet with dill and lemon juice
- Steamed broccoli, a lot
- Blueberries, or perhaps a spinach salad with peppers, red onions, raspberries and a handful of walnuts, balsamic vinaigrette on top.
Even if we have a large and fatty cut of salmon we're looking at 350 calories for the typical person, plus another hundred or so between fruit and walnuts. Calories from fibrous vegetables and fruits (assuming they're low on sugar) are essentially negligible. A ~450 calorie meal that's packed with vitamins, minerals, protein, omega-3 fatty acids (double whammy between the salmon and walnuts. On top of this we're going to see almost no insulin spike and it will be incredibly filling. Replacing any of the ingredients with bread or rice would greatly increase the calories, spike insulin more than we want, and decrease nutrients, let alone comparing this lovely salmon meal to a a different dinner such as a bowl of pasta.
The take home message here isn't that carbohydrates are bad, but that spiking insulin is going to be very detrimental to fat loss, and as such we should be considering the kinds of carbohydrates we're putting in our mouths to ensure that they are nutritious and aren't going to kick us off the fat loss bandwagon. Quality of food is important, and a calorie isn't a calorie isn't a calorie.
The short(ish) of it: the nature of Paleolithic eating generally means you will be consuming more fats and fewer carbohydrates than you currently do. Fat is good for you, especially from high quality sources like salmon, grass-fed beef, nuts, olive oil, and avocados. The literature and biochemistry points out how lower carbohydrate diets are more effective for fat loss and also tend to improve cardiovascular disease measures more than low-fat diets. Insulin is released in response to rises in blood glucose levels (most dramatically increased by the consumption of sugars and carbohydrates from grains) and stores energy. Glucagon is its "opposite" and releases energy (like fatty acids from fat stores), but is inhibited by higher levels of glucose. Protein and fat keep you fuller, longer, so you aren't as hungry even when calorie levels go below maintenance. Carbohydrates are good, but we want to get them from vegetable sources, low sugar fruit (berries, melons), and the occasional yam/sweet potato/similar food.
Post questions to comments. The next Paleo blog will focus on markers of health for things such as cardiovascular disease and diabetes, and how a Paleo-based diet may be beneficial to these.
- Jonathan
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