Concerns about the effects of sugar on health and body composition are among the most common we encounter in our nutrition coaching practice. Consuming too much sugar is, in most contexts, not great for health. But, we need to add some nuance to this, as diets high in sugar often have other poor characteristics, such as
being rich in refined grains, added fats, low in fibre, and calorie dense. Nutrient-poor, calorie-rich diets are the opposite of what we want, but the blame can't be laid squarely at the feet of sugar.
Does sugar cause weight gain?
To cut to the chase, eating sugar does not cause weight gain or harm weight loss when calories are controlled. You can eat sweets everyday and still lose fat. But, it's not going to be easy. You see, we need to move beyond just "calories" and consider what actually regulates our appetite best. After all, if you feel fuller after a meal, that is going to reduce subsequent caloric consumption. And that's the problem with
sugar-rich foods, they are delicious and very easy to overeat.
Not all "sugary" foods, however, and in reality, it's often sugar + fat (and often salt and refined grains too, along with other flavourings) that drive overconsumption most. Think about it, when was the last time you started scoffing down granulated sugar from the jar?
Chocolate = sugar + fat.
Ice cream = sugar + fat.
Cake = sugar + fat.
Cookies = sugar + fat.
Clearly, these are foods that are very easy to overeat, but when people look at them, they often think of the sugar. Should the added fat be blamed instead? No. The point is that we need to consider foods as a whole and the effect they have on our intake, rather than myopically focusing on single nutrients.
Fruit? Sugar...
Jelly sweets? Sugar...
Are fruit and jelly sweets equally easy to overeat? No. Are they equally healthy? No. If you eat fruit every day in large quantities, you will probably improve your health and make weight loss or maintenance easier. If you ear jelly sweets every day in large quantities, hmmm, what do you think?
One-line summary: Sugar drives weight gain by making foods more tasty and causing you to want more, but it does not independently cause fat gain independent of overall energy / calories in the diet.
Does sugar harm health?
The story is somewhat similar as it relates to health, and it's probably most helpful to consider substitution effects here. If you substitute whole-grains (e.g. oats) in your diet with sugar, that is a net negative for health. If you substitute unsaturated fat (e.g. olive
oil) in your diet with sugar, that is a net negative for health. If you substitute saturated fats (e.g. butter) in your diet with sugar, the effect is probably neutral. And again, the source of sugar matters, so if that sugar came from fruit, the effect of the substitution would be swayed in the positive direction.
This concept of substitution is important when
thinking about this issue. You see, the decision to add something to your diet, assuming you keep calories equal, is a decision to remove something else. Therefore, if more of your calories consist of sugar-rich foods, this may result in you displacing fibrous foods, non-starchy vegetables, or sources of protein. When you displace healthful foods, you now have the displacement effect that may cause harm, regardless of what food you added. This is why a diet composed of just one food, regardless
of what food that is, would be deemed unhealthy, even though that food in isolation may be considered positive for health.
This brings us to practical application. Generally speaking, a limit of 5-10% of total calories from added sugars is reasonable. I would not place a limit on fruit intake, nor sugars coming from vegetables. When considering this 5-10% limit, this
should be applied to the general population, as athletes partaking in hard training and burning through lots of carbs can consume more without issue (and may even benefit from doing so).
At 2400 calories, 10% of daily calories = 240, which equates to 60g of added sugars per day. Therefore, you'd be looking at 30-60g per day as your limit, which serves as a proxy
for the quality of the remainder of your diet also. This is also why it's important to consider sugar as a % of calories rather than an absolute level. 60g added sugar is a LOT for someone on just 100g carbs per day, as this would tell us that they are consuming just 40g carbs from more healthful sources like fruits, vegetables, whole-grains, legumes, etc. But, for someone on 600g carbs (like me today as I carb-load for a running event!), 60g is nothing.
As always, context matters.
One-line summary: Sugar can harm health, primarily via driving overconsumption and displacing more beneficial foods in the diet, but it should not be viewed as inherently toxic or harmful, particularly when
consumed via health-promoting foods like fruits or for the purpose of sports performance.
If you have any further questions about sugar, you are welcome to respond to this email and I will get back to you.
