My current view of the Zone diet

I got this question on via Twitter a couple of weeks back: “How are you a Paleo AND Zone nutritionist when they have some major differences on what they allow as part of the diet?”

As you may have noticed my blog is called Paleo Zone. The Zone bit refers to the Zone diet. It’s time to pass on my thoughts about where I stand with it. There are many in the Paleo community who are rather dismissive (putting it mildly) of Barry Sears and his dietary philosophy. (5 fries anyone?) Sears, a biochemist is known for his design of the Zone diet with it’s protein, carb, fat ratio of 30:40:30 (by calories)  and his theory that we should strictly adhere to this ratio no matter what -every time we eat. Yes I’ve been to lectures where he is adamant if wine and chicken are all one is willing to eat for dinner – it should be in the precise zone ratio. (Yeah I know, it sounds kind of nutty when put like that)

My Zone diet history and why I got super enthusiastic about it

Some history – I’ve written about this before – but a quick recap: 16 years ago I read “Enter the Zone” by Sears. At that time I was not a nutritionist  – I was working as a seating and positioning specialist, a designer of equipment for people with severe disabilities. I taught an ergonomics course at University. I was at a strange place in life, losing interest in my career, and following another interest (but not passion)- I was in my first year of a Fine Arts degree.

The Zone diet plus omega 3 had a huge health impact, and also ignited a passion, a new interest. The Zone diet dealt with reactive hypoglycemia, PMS and menstrual pain. I lost weight, gained energy, experienced increased mental focus and fantastic appetite control. In short I was in awe of the difference changing my diet made.

I gradually shifted my career from design (I left art school – being an artist was not where my head was at) to teaching Zone principles. (I am also a registered Nurse and obtained a Zone Instructors certificate in the USA) I saw the majority of my clients get amazing results similar to what I had achieved.

Why my Zone diet results were erratic, and Paleo provided the key

I was introduced to Paleo food choices just over 2 years ago. When I took out non Paleo foods; grains, legumes and dairy – my results were more profound and consistent, it illuminated why the Zone diet had worked so incredibly well for me when I started it, and why, over the 13 years I followed it results were erratic – i.e I sometimes got PMS and joint inflammation, and sometimes not. Robb Wolf posted my story here: The Zone, better with paleo foods

The Zone diet

So lets take a look at the original Zone diet – Classic Zone it is sometimes called. The one I originally had such success on. Sears actually looked to paleolithic research when he designed it and based his protein: carb: fat ratio on Cordain’s research into the ratio of macronutrients consumed by hunter / gatherers. In “The Paleo Diet” Cordain states these are Protein: 19-35%, Carbohydrate: 22-40%, and Fat: 28-47% of calories.

So Sears took and average as his basis for the Zone diet’s ratio of protein 30%, carbohydrates 40% calories and fat 30%. Sears also notes that there is a continuum – that the protein: carbohydrate ratio may vary depending on insulin response of each person. And  if you don’t need to lose weight, additional fats should be added to increase calories – primarily mono-unsaturated fats, olive oil and macadamia for example.

The Zone protein and carbohydrate prescription:

We need enough to maintain lean body mass. The amount required (and most research would agree) is 0.5 – 1 gram per pound of lean body weight, the amount depends on exercise load – more exercise requires more protein. A fairly standard equation – enough but not excess. What about carbohydrates? Well having decided on a protein to carb ratio based on the Paleo average, this meant 4 grams of carbohydrates to every 3 grams of protein. A person then would get a minimum of 100 grams carbs and up depending on body size.

Why this precise protein to carbohydrate ratio?

Each macronutrient triggers the secretion of different hormones. Insulin is secreted in response to carbohydrates (i.e blood sugar elevations), protein triggers glucagon. Keeping these hormones balanced after each meal Sears says is critical for the production of eicosanoid hormones in an ideal balance. (Insulin increases delta-5-desaturase activity which increases arachidonic acid (AA) formation from Linoleic acid,  which then goes on to build inflammatory eicosanoid hormones). Sears theory is that by controlling insulin: glucagon ratio you also keep pro and anti-inflammatory eicosanoid hormones in balance.

Food choice:

Carbohydrates: an emphasis on low density low GI.

Sears states in Enter the Zone, p101 – “…lean meat, fruits, and vegetables were the preferred menu – a menu in harmony with human genetic makeup.” However he goes on to say that the most important aspect of the paleo diet is it’s protein to carbohydrate ratio which keeps insulin, glucagon and eicosanoid hormones “on an even keel” On the very next page Sears goes on to say “All this dietary and genetic harmony was disrupted about ten thousand years ago with the development of agriculture. With agriculture came two entirely new additions to the human diet: grains and dairy” …”In fact, by and large humankind has been genetically unable to cope with these foods” (Emphasis Sears, page 102 “Enter the Zone”) However Sears sole focus is the the blood sugar and insulin response, (the glycemic index) of these foods, nowhere does he refer to the anti-nutrient contained in grains and legumes, despite using papers from Paleo diet researchers to design his PCF ratio. I.e. Sears sole reason for minimising grains is because they are “high density, high glycemic index carbohydrates”

Fats: restrict foods high in Arachidonic Acid (AA) and saturated fat.

Sears recommends restricting foods with a high AA content: egg yolks, fatty red meat and organ meats, AA being the precursor fats to pro-inflammatory eicosanoids. Limit saturated fat, as it increases insulin resistance. Stick to mono-unsaturated fat, as it has no effect on insulin. Sears also emphasises a diet low in Omega 6 linoleic acid particularly if you you have had cancer.

When I initially started the Zone diet, I virtually cut out gluten grains. As time went on, I used them more, especially when I found low GI breads. Little did I realise at the time, my erratic  results on the Zone diet were purely related to the amount of non paleo foods especially gluten grains. I was only to discover this when I switched to paleo eating 2 1/2 years ago.

(Given the research Sears had access to – I just don’t get him ignoring the issue of human evolution and our incompatibility with the anti-nutrients in grains)

So when I started eating the Zone diet – by default I followed a Primal diet (paleo plus dairy) – a diet devoid of gluten grains (being a good girl I followed advice and avoided the ‘unfavourable’ carbs)

Sears found he got stunning results in his diet trials with people, and attributed them to the reduced high glycemic load carbohydrates, I would argue that yes, while this made a difference – the change in food quality must have also contributed.

What science shows – does the Zone ratio work?

So lets have a look – how much difference does the ratio make – especially when combined with food quality? A very illustrative study was done in 1999. This crossover study measures the effect of a Zone (actually a paleo zone) meal compared with a typical high carbohydrate grain / dairy based meal perfectly.

The study (High Glycemic Index Foods, Overeating, and Obesity):

• 12 obese teenage boys, crossover study, 3 separate 24 hour admissions to hospital, 1 -2 weeks washout periods in between
• 3 different meals were evaluated, high GI, moderate GI and low GI, one on each admission.
• The boys ate the same meal for breakfast and lunch and were allowed to eat as much or little as they liked for the rest of the day. The exact amount consumed was measured.
• A number of measurements were taken – blood sugar, insulin, glucagon, epinephrine, hunger ratings.

Here are the actual meals, two meals are typically high carbohydrate / grain /dairy – but with different glycemic index. The other is contains paleo foods in a Zone macronutrient ratio – more protein and fat, less carbohydrate.

Results: The graphs speak for themselves:

Hormonal and metabolic changes after test breakfasts. Plot symbols: square, high-GI meal; circle, medium-GI meal; triangle, low-GI meal.

Note: Blood glucose and insulin response was far lower after paleo zone meal. After the highest GI meal, blood sugar dropped below base line around 3.5 hours and epinephrine increased. Glucagon rose in the meal with protein – but was suppressed in the low protein meal.
Change in hunger after test breakfasts. Hunger is determined by a 10-cm analog scale.

Cumulative food intake after test lunches. Food intake is quantitated as total energy consumed, expressed in megajoules, and normalized to a predicted RMR of 8.4 mJ (2000 kcal).

As you can see the difference between the paleo zone meal and the high carb, high GI meal in terms of hunger and consequent food consumption is huge. 80% more food was eaten after lunch following the high GI meal. Those eating a paleo zone meal did not start eating before 2 hours.

This is a perfect illustration of why the zone diet without grains worked so well for me (and of course others) providing good blood sugar and hunger control. But I would note: the ratio of protein carb and fat does not need to be exactly zone to elicit favourable glucose insulin response and hunger control. There is probably a fair amount of leeway with ratios.

(A weakness in this study is there is no control for paleo / non paleo foods. The zone balance is paleo, the high carb is not. This may have impacted the results.)

What is useful about the Zone diet?

My experience when helping people with their diet is that everyone wants to know – how much do I eat? What should a meal look like? The Zone meal protein prescription, and meal template is a great starting point for the average overweight person. Sears calculation for protein amount, and meal size works well for most people. (It worked exceptionally well for me)

But – if you eat real food i.e paleo, won’t people eat the right amount?

I know there are those in the paleo community who recommend just eating real food. However I’ve seen people “just eat real food” and put on weight. Calories do count, and you can overeat paleo foods. I often put on weight when I eat the amount I feel like on real food. Another issue I see frequently is people, especially those who are active, cut their carbs too low on paleo. They switch from dense grains, refined carbs and sugars to non starch vegetables – often cutting carbs by 80 – 90%, leaving them fatigued, with poor recovery after exercise and sleep problems. Using the zone carb amount as a guideline ensures adequate carbs, while still being significantly less than the SAD.

I don’t think one needs to get too fussed about using Zone blocks, I use this as a Zone meal guideline, and it works perfectly well for most people:

My Zone portions on a plate – note: I have emphasised foods that I think are important – this is not Sears viewpoint on foods.

• Protein – size and thickness of palm of your hand (approx 1oo – 250 grams), If fish or seafood – closer to a hand size or two palms. If very active and bigger built – up to two palms may be needed.  Sears says lean, I think ‘leanish’, fattier okay if you don’t need to lose weight AND fat is good quality – low omega 6 and grassfed. Use organ meats / bone broths weekly. High omega 3 seafood several times week. (Limit or avoid processed meats, dairy protein. Avoid legume protein / soy)
• Carbohydrates: 2 / 3 plate fruit and vegetables: Approximately 1/2 – 1 fist starchy vegetable. Lots of non starch veg, go for many colours. Fruit 0 -2 serves day, berries are best. Use fermented vegetables sometimes. (No grains, legumes)
• Fats: A teaspoon or more of fat. (Sears says about 1/2 a thumb, I think more is needed – about a thumb size) More if weight is not an issue. Low omega 6 oils, nuts and fats. Macadamia, coconut, meat fat like tallow, grassfed ghee. Oily fish like wild salmon. (No chemically altered fats – trans, inter-esterified, vegetable seed oils, peanuts)

To sum up:

The Zone eating template is a useful tool for getting the amount of protein and carbohydrates about right, and the ratio of protein to carbohydrates is a good starting place for your average overweight, light to moderate exerciser. It provides a controlled meal size, and gives good blood sugar levels and hunger control for most. Adding good fats as needed (a not well known zone concept), is one that works. Decreasing omega 6, increasing omega 3, no argument there.

However only adding monounsaturated fats like olive oil and almonds can lead to too much omega 6 being eaten. There is general agreement now that saturated fats aren’t all that bad, and some are good for us like MCT’s in coconut oil. So I would recommend adding only low omega 6 fats and oils, even if they contain saturated fat.

However for active people, athletes more food – both protein and carbs, is often needed to get good performance and feel great. For those with insulin resistance, and poor blood sugar control – much lower carbohydrates (and higher fat) may be required to get blood sugar levels down.

A note about moderate vs low carb – my experience

The Zone is a moderate carb diet, it is not a very low carb or zero carb diet. There is a view that you can only lose weight by dropping carbs really low – 10 – 30 grams day. That may be some people’s experience but it is not mine. Very low carbs at a meal for me is not satisfying. My theory is that I need to elevate my blood sugar and insulin a certain amount for satiety. Without carbs – I keep looking for food, I just don’t feel right. 1/2 a cup of sweet potato with my protein and I’m set for hours. “Didn’t you try adding more fat?” I’ve been asked – yes I did, but I often end up putting on weight with a low carb high fat diet. Fat does not have the immediate satiety and feeling of fullness that a moderate amount of starchy carbs do. It’s just easy for me to get the food amount right and feel right on moderate carbs.

The biggest issues I have with the Dr Sears Zone diet:

My main beef with Sears is that his only criteria for choosing carbohydrates is the glycemic index and the glycemic load. This makes fructose a good carbohydrate and carrots bad, and that is just nuts. He completely ignores the anti-nutrient issue with grains and legumes and the problems with fructose. In my experience and many clients now, food quality is paramount. Portion control and food amounts are next, and that is where the Zone diet can help. However with rough guidelines and an emphasis on food quality, for many, portion control follows on without having to make a big deal out of it.

The other issue is the fear of Arachidonic Acid. AA is an essential fat. Yes it is the precursor of pro-inflammatory hormones, but by cutting the foods with AA in it we cut foods that have lots of useful nutrients. Liver, organ meats and egg yolks are high in many nutrients and some that are hard to get in other foods,  like choline, vitamin A, and copper. I think it is best to minimise omega 6 linoleic acid, which you convert to AA, instead of cutting out nutrient rich foods that contain a little AA.

Saying all this – the zone ratio and food amounts are my fall back when weight sneaks on – and yes purely by eating too much!

As for the New Zone Foods: they’re 30:40:30 Low GI madness

Post script: Sears promoted and wrote about more than just a food ratio – and he deserves recognition for this. (He was by no means the only person to emphasise these, but this sometimes gets lost as we think of Sears as the 30:40:30 man)

In the Anti-aging Zone covers diet and lifestyle in relationship to it’s effects on aging and hormones. He covers a number of hormones, including the sex hormones, serotonin, melatonin, DHEA,cortisol, growth hormone and thyroid hormones. His anti-aging prescription: A balanced diet high nutrient, calorie restricted diet that controls blood sugar and insulin levels, plus selected supplements. Moderate exercise and cortisol reduction are stressed.

The Anti-Inflammation Zone covers silent inflammation, the inflammation you don’t feel – that is the basis of diseases of aging. He covers anti-inflammatory diet and lifestyle strategies, including omega 3, anti-inflammatory foods and supplements.

The OmegaRx Zone describes the benefits, for many diseases, of taking high quality omega 3 fish oil, and minimising omega 6 oils to get an ideal EPA:AA ratio of fatty acids in plasma phospholipids in the blood.

In his most recent book Toxic Fat, Sears describes the perfect nutritional storm that contributes to weight gain: large amounts of high glycemic index refined carbohydrates, high omega 6 oil intake, toxins like PCBs and BPA that get stored in fat, and low omega 3 intake.   He describes (again!) diet for reversing this – a low GI balanced diet, that controls insulin, blood sugar and appetite and increasing omega 3 and decreasing omega 6.

More reading:

”Most people are simply not designed to eat pasta”:evolutionary explanations for obesity in the low-carbohydrate diet movement” Christine Knight

And just released from CrossFit’s Greg Glassman, contains course language: An Interview with Fast Company Magazine (I don’t subscribe to all that Glassman says – he misses the point with paleo)

This very recent study shows changes in gene expression when people eat close to Zone balanced meals: Balanced Caloric Macronutrient Composition Downregulates Immunological Gene Expression in Human Blood Cells—Adipose Tissue Diverges