A Doctor Explains: How Sugar and Fat Affect Your Body 

For a long time, the word on the street has been that we shouldn’t eat too much fat. Fat notably contains more calories than proteins and carbohydrates, which is why many people think it will cause you to gain weight (and get sick). Low-fat goods are shoved down your throat and egg white omelets have become the new holy grail.

Unfortunately, this hasn’t led to a significant increase in the health of the average person: The number of people who are overweight and/or suffering from cardiovascular diseases just keeps rising. There are several reasons for this. One of them is sugar: Low-fat foods often contain less fat, but more sugar and/or sugar substitutes. We now know that a fat-restricted diet with more carbohydrates increases your risk of cardiovascular disease (1).

So, is sugar bad for you then?

To answer this, we’ll need to take you through a bit of chemistry. What exactly are sugars and what do they do to your body? 

Sugars are classed as carbohydrates. Like proteins and fats, carbohydrates occur in (natural) foods. A carbohydrate is often a chain, consisting of basic sugars. The chain can be long or short.

– Your body has to break down longer chains first and that takes time. The longer the chain, the longer it takes to break everything down. Once a long carbohydrate chain has been broken down into basic sugar (glucose), our bodies can absorb it and use it. You might know these long chains as “slow-release carbs”, such as whole grain cereals, pulses and vegetables.

– Short chains, consisting of one basic sugar (glucose), can be absorbed and used by our bodies right away. Mostly, the “added sugar” in a product is basic sugar, which is absorbed (too) quickly by your body. We’re talking cookies, flavored yogurt, and ready-made meals. However white bread, white rice and pasta also consist mainly of short chains. Short chains are also known as “fast-digesting carbs”. 

So, here’s the crux: In nature you mainly find slow-release carbs. We’re talking about the fiber in vegetables and the starch in potatoes and grains. When you eat these, your body needs time to break down the sugar chains. The glucose is released gradually, a bit at a time, which is nice and restful for your body. It can keep up with the changes, so to speak.

Past vs. present

Despite this, we as humans are pretty partial to sweet treats. The sugar activates your reward center: You want more… And more! We naturally don’t have a stop switch when it comes to sweet stuff. This helped us to survive in a natural environment in earlier times, when periods of abundance were interspersed with periods of scarcity. This means your instincts are telling you that you want sugar. 

However, we no longer live in the natural world where our access to food is limited. Instead, we live in an artificial food landscape, where supermarkets are full of foods from all over the world. The industry keeps adding sugars left, right and center, and at home the fridge and cabinets are all generously stocked. Processed products with short sugar chains are everywhere. This abundance of (quick-release) sugars is hard for your defenseless sweet tooth to resist.

What happens to your body when you eat sugar?

When you eat quick-release sugars, lots of glucose abruptly enters your blood, causing your blood sugar to spike. This is intense for your body and it tries to expel this excess of glucose from your blood and cells. It does this using the hormone insulin, which is produced by the pancreas. 

The pancreas has to produce insulin at full speed. When the sugar levels in the blood return to normal again, the pancreas receives a signal to stop producing insulin. Since it was really on a roll, it takes a while for the production level to drop back down. 

A bit too much insulin is always produced, causing a shortage of glucose in your blood. The result? A blood sugar dip. You feel tired, get grumpy, and your ability to concentrate might drop. Maybe you’re already feeling it, so you go in search of something that will boost your blood sugar level again: a cookie, a piece of chocolate, a tasty dessert… And, so the story continues.

A prolonged fluctuation in blood sugar levels

For a day, these fluctuations in your blood sugar aren’t a problem. But it becomes a problem when large blood sugar fluctuations occur over an extended period of time. At some point, high insulin levels will cause your body to stop ‘listening properly’ to insulin. Your cells become resistant to insulin, so to speak. 

Insulin-resistant cells don’t absorb glucose as quickly. The result is that your body must produce more and more insulin to get the same effect as before. Increased insulin production makes your insulin resistance even worse. It’s a vicious cycle. 

Over time, this can result in type 2 diabetes. In this case, too little sugar goes from the blood into the cells and the blood sugar level remains high despite high insulin levels. Raised glucose and insulin levels have a negative effect on the body: They increase your risk of cardiovascular disease and lead to an increase in (oxidative) stress, causing low-grade (silent or chronic) inflammation.

How can you maintain regular blood sugar and insulin levels?

Foods that consist of quick-release sugars cause these undesirable peaks in blood sugar and insulin levels. When your blood sugar levels are greatly fluctuating, chances are you’ll tend to want to eat unhealthy foods (i.e., sugary foods). However, a low-carb meal causes a subtle increase in insulin, which means your levels drop quickly afterwards (2)

It’s actually good for your body if your insulin levels have time to drop. This could be between meals, but also at night. However, this won’t happen if you eat often or you’re constantly snacking.

What can you do?

Opt for slow-release carbohydrates. In practice these are unprocessed foods that don’t cause extreme spikes in your blood sugar levels. Consider:

– Whole grain cereals, such as brown rice, oatmeal, barely, and quinoa

– Berries

– Vegetables

– Pulses

As much as possible, avoid fast-release carbohydrates with a high glycemic index, such as:

– White rice

– White bread

– Snacks, such as pastries, cookies, desserts and chips

– Sugary drinks

– Cooking with pre-packaged ingredients

Totally avoiding carbohydrates is not a good idea: They give us energy, fiber and certain vitamins and minerals (such as iron, B vitamins, magnesium and phosphorus). It’s all about balance.

And how does this relate to fats?

Just as with sugars, there are also different types of fats. On the one hand, there are saturated fats and trans fats, but on the other hand there are “vital fats” rich in omega 3. The last group gives you a pleasant satiated feeling that helps you to eat less. Your body needs fats to function properly. Here again, it’s important to find the right balance (3). To do this, opt for the following foods: 

– Nuts and seeds

– Olives

– Olive oil, linseed oil and pumpkin seed oil

– Avocado

– Oily fish, such as herring, mackerel, salmon and sardines

– Sea vegetables

– Green leafy vegetables

– Eggs

– Poultry

As much as possible, avoid saturated fats and trans fats (4). You find these in: 

– Dairy products, such as milk and the meat from cows and sheep

– Palm oil and products its used in, such as cake, pastries, and snacks

– Margarine, low-fat spreads

– Fried foods

– Ready-made meals

Eat enough, but not too much

As well as what you eat, how much you eat is also important. Even if you only buy healthy foods, you’ll still gain weight if you eat too much. Anything you don’t burn off, is simply stored in your body as fat mass. That applies just as much to carbohydrates and egg whites as it does to fats. A high fat mass can lead to obesity, with all the associated health risks, such as cardiovascular diseases, musculoskeletal disorders and type 2 diabetes. 

So, what exactly is “enough”? “Hara hachi bu” is what the Japanese say. It means: “Eat until you’re 80 percent full”. Don’t eat too fast because it takes time for your body to feel full (twenty minutes on average). Putting your cutlery down every once in a while, and chewing extra well will help you stretch out the time. 

If you’d like to learn more or discuss your situation with one of our dietitians, book a consultation.