When it comes to sugar and carbs it seems that some have got the wrong end of the stick and proceed to beat about the bush with it. Sugar has been called 'white poison', governments have brought in 'sugar tax' and it's been said that sugar is highly addictive. It can be psychologically comforting to identify a bogeyman. The idea is so exciting that it's spawned many a book, blog, video and a cult-like following.
However, there's good reason not to be too hasty in blaming a single enemy. Fat used to be the bad-guy. These days it's sugar that gets the headlines. Next it might be protein and if we avoid all three of these there'll be pretty much nothing left to eat.
For weight management, how is it possible that people see results in following a low carbohydrate diet (i.e. avoiding sugar), while also true that they see results by eating just the opposite way i.e. a low fat diet. Many books and programs have been written espousing one or the other diet as the be-all and end-all.
If you've ever tried to lose weight on a low carb diet you'll know that eating carbs while on your low carb diet will sabotage your results. Conversely if you've tried a low fat diet, then adding fat will not go well either. Of course, the clue's in the name of these respective diets. But how is it that these apparently opposing diets can help with weight management (at least in the short term)? On a 'high fat' diet people will lose weight if they avoid carbohydrates. But, on a 'high carb' diet, people lose weight providing they avoid fat. This is evidence that no single macro-nutrient on its own - carb or fat - is the cause of weight gain, regardless of how many diet books take one side or the other.
The short answer is that both diets could help reduce food cravings. That could be the real underlying problem - cravings that make it hard to stop eating when you should feel full - not because of a single macro-nutrient baddy such as carbs or fats, but by a combination of the two in high fat / high sugar foods, especially when in an optimal 50% to 50% caloric ratio as we'll discuss below. No doubt other factors come into play as well, but here we'll discuss the 50% to 50% caloric ratio of carbs to fat. If you're addicted to eating and can't stop, you'll no doubt gain the pounds, which is why the causes of food addiction need to be addressed.
Sugar is Addictive. Or is it?
One of the highest sugar diets in existence is the Fruitarian diet. Look at Fruitarians and you will see a bunch of slim people, in spite of all that sugar. It's hard to get addicted to fruit. If you've gone onto a Fruitarian diet then you are likely consuming more carbs than you ever did before, but like most fruitarians, you will probably still lose weight. The easy conclusion is that you're consuming fewer calories, because everyone knows it's "all about the calories". But if it was as simple as telling people to cut calories, there'd be no obesity epidemic, so there's evidently something bigger at play - a driving force making it difficult to moderate eating habits.
So which is the prime suspect, sugar or fat? Well neither - and both. Put simply, fat with carbs is the culprit. Both combined together. Why? Because the combination of the two may lead to compulsive eating, or put another way, foods containing high amounts of carbs and fat together can cause food cravings which in turn lead to weight gain. Each of these two macro-nutrients on their own when consumed without the other, is not likely to cause weight gain, which is shown in a study below.
Let's call it 50:50 (or Fifty:Fifty), because it turns out that with foods that are rich in fat and sugar, the closer we get to 50% fat calories combined with 50% carb calories, the more the likelihood of causing overeating in some people. A 50:50 diet was tested on rats and the results were shocking (literally) because the rats would put up with mild electric shocks to get to their cheesecake. (Cheesecake is an ideal 50:50 food source of fat:carb). They stopped eating the regular healthy food that was there, in favour of getting their calories from cheesecake, even when given a prior warning light that they would have to walk over a mild electric shock to the food source. Their strong urge for high sugar/fat foods lead to continuous grazing, with no 'off switch’. They gained a massive amount of weight, became sedentary, obese, and slept more. There was also a separate test giving free access to high sugar soda, and another separate opposite high-fat diet. The results of 'sugar alone' was no weight gain and the 'fat-alone' resulted in a small weight gain, but nothing when compared with the 50:50 combo. Out of all the experiments, it was found that the closer to the 50:50 ratio of carbs to fats, the more weight gain happened. The conclusion was that the reward systems in the brain are being impacted far more when you consume food that's rich in fat and sugar than when consuming either fat or sugar alone. The study by Johnson and Kenny showing this brain reward deficit leading to over-eating, is referenced at the foot of this page.
So when we hear about 'sugar addiction', yes it may be true, but only when combined with fat. When you see or read articles about sugar being the enemy, they're often accompanied with a barrage of photos of sugar laden cakes, ice-cream, cookies and chocolate muffins. But all these moreish foods are actually ~50:50 combo foods. They don't contain just sugar, they have fat too, in an almost equal caloric ratio. The foods that people quote as evidence of sugar addiction are addictive not because of the sugar per se, but because of the cocktail of sugar with fat in equally high levels.
If sugar was addictive on its own then why aren't people sneaking spoonfuls of it? There would be hidden spoons inside sugar bags. Instead, it's things like biscuits (~50:50), crisps (~50:50), doughnuts (~50:50), fries (~50:50), snack bars (~50:50), ice-cream (~50:50), pies (~50:50) and so on, that can be difficult to cut down on. It seems that manufacturers know how to hijack our taste buds when they create their 50:50 products. This is one reason why we generally accept that processed foods are best avoided if we want to lose weight. It's not by accident that many manufactured food products happen to contain the magic 50:50 carb/fat combo.
What about nature? Does nature have 50:50 foods? No. Wholefoods deliver either fat or carbs, not both together. The fat to carb ratios in wholefoods such as fruit, vegetables and nuts rarely exceed 80%:20%. And of course, foods from nature tends to contain other nutrients contributing to the overall calories, making them less rich in sugar and fat overall. Fruits are high in sugar and fibre, with virtually no fat. Vegetables tend to be low in both fat and carbs, being high in fibre. Avocados, nuts and coconuts are mostly fat and fibre. Wholefoods never get anywhere close to 50%:50%. It’s a manufactured combination that can’t be found anywhere in nature. This could be why sticking to a diet of wholefoods is one of the healthiest ways to lose weight.
50:50 foods are extremely palatable man-made concoctions and come in many forms, both sweet and savoury. The next time you find yourself unable to stop eating something even though you know you're not truly hungry, have a look at the nutrition info for the ratio of fat to carbs. Bear in mind that fat has 9 calories per gram and carbs have 4 calories, so when working out caloric values this should be factored in.
Of course, not all carbs and fats are created equal, and the degree to which they are processed by manufacturers may play a role in how the body deals with them. We should mention that not all carbs are sugar, but all sugars are carbs. Here, we just looked at the ratios of fat to carbs, which doesn't tell the whole story. It's obviously a deep subject that divides opinion, even among 'experts', and we don't claim to cover all the bases here. Some would say that processed foods are not actually foods at all, so we've use the term 'foods' loosely. There are numerous other factors which may contribute to obesity not limited to lifestyle, genetics, MSG, aspartame, calorie density, nutrient density and so on. Food addiction and obesity are complex issues and research shows it may be more to do with combinations of macro-nutrients, rather than blaming one single macro-nutrient such as sugar or fat.
Johnson and Kenny study showing brain reward deficit: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2947358/
We do not support animal testing.
Horizon Sugar v Fat showing experiment on identical twins: https://www.bbc.co.uk/programmes/b03t8r4h