Does sugar interfere with weight loss? Should I take up a no-sugar weight loss diet? In fact, we could limit ourselves to one simple answer to these questions:
Yes, it interferes if it causes non-compliance with the energy deficit – the only condition necessary to reduce the body fat stores in a non-surgical way. This reason can be expressed both in direct energy supply, that is, we eat a lot of sugar, thereby increasing the calorie content of the diet, and in indirect.
For example, sugar, or rather products containing it, can provoke unplanned food consumption, in excess of the established dietary plan. You bit off a piece of chocolate and realized that you wouldn’t be able to stop until you eat all of it.
Stereotypical Views on the No-Sugar Weight Loss Diet
But most people far from modern science, which include not only ordinary people who want to lose weight, but bloggers and even real doctors who call themselves nutritionists, are unlikely to accept such an ordinary explanation.
The stereotype “want to lose weight – remove the sweets” prevailing in society is so firmly stuck in the brain that it is perceived as an axiom. For many sugar is not one of the types of carbohydrates and, accordingly, a source of energy, but something more. A substance that has literally magical properties to increase fat or interfere with weight loss. And this “magic“, as a rule, is based either on outdated theories or simply on personal fantasies and beliefs. However, it is worth looking at least superficially at objective sources of information, as it turns out that everything is simple.
Everything is exactly as it is written at the beginning.
Studies on the effects of sugar in the diet for weight loss
So, according to the results of a systematic study and meta-analysis of a large number of serious cohort studies (randomized and controlled) – a total of 68 publications – about how sugar in the diet affects changes in body weight in children and adults, we can conclude that in people that do not control consumed food strictly (ad libitum diets), the main factor determining weight is the consumption of sugar (both in direct form and in the form of sweet drinks).
An increase in the amount of sugar in the diet causes an increase in body weight, a decrease – a decrease in weight. The research results clearly show that the mechanism of influence of the amount of sugar in the diet on body weight is a violation of the energy balance (for example, the excess of energy intake over the body’s needs), and not the biochemical and physiological characteristics of the metabolism of simple sugars in the body.
This conclusion is confirmed by the results of 12 other studies (with periods of 0.5-6 months), in which it was found that the replacement of simple sugars with other carbohydrates (in particular, in a lower glycemic index) on the background of an isocaloric (same in calorie) diet did not lead to a change in body weight. 
Glycemic index and sugar harm
The high glycemic index (GI) is one of the common reasons that explain the harmful effects of sugar on weight loss. “Nutrition gurus” believe that “fast” carbohydrates turn into fat instead of being used by cells directly as energy. There is no scientific evidence for this, just as there is no logic in such statements.
If, against the background of energy deficiency, the sugars consumed are not used by the cells, then, in fact, the body receives even less energy, which means that even more is necessary to compensate for the missing from internal reserves, including fat.
In fact, scientists have already put an end to the issue of the influence of GI used carbohydrates on weight loss results. A meta-review of studies on the importance of glycemic index and glycemic load for body weight, diabetes, and cardiovascular disease (includes 73 randomized controlled trials) says literally the following:
“Existing intervention studies do not have enough data to ascertain the benefits of a low-calorie diet aimed at weight loss, low-GI carbohydrate sources. Despite the fact that some short-term studies have shown the benefits of low-GI carbohydrates to reduce weight as soon as possible, studies with a high degree of control over the foods consumed by the experiment participants show that a change in the GI of the carbohydrates included in the diet does not affect the final changes in body weight.” 
The effect of fast and slow carbohydrates on lipogenesis
It is not clear at all where the information that fast carbohydrates turn into fat more than slow ones came from. The most reliable sources of scientific information are studies, but they do not indicate this.
The topic “The relationship of the glycemic index with human lipogenesis” was dedicated to a special scientific conference that did not reveal a significant difference in the scale of synthesis of fat from carbohydrates as a result of polysaccharides (in particular, starch), mono- and disaccharides, despite differences in such indicators as blood insulin and glucose levels:
“A certain relationship between the glycemic index of carbohydrates absorbed during nutrition and its ability to activate lipogenesis requires further and more thorough study.” 
Moreover, the whole carbohydrate-insulin hypothesis of obesity, which just did endow carbohydrates in general and sugar in particular, was higher in their ability to accumulate fat compared to dietary fats, has not yet been confirmed.
A systematic review and meta-analysis of the Obesity Energetics: Body Weight Regulation and the Effects of Diet Composition provides compelling and comprehensive data on the relationship between dietary composition, energy balance, mechanism, and the risk of obesity. The review included 32 randomized controlled trials with the isocaloric replacement of dietary carbohydrates with fat, with the same protein content in food.
Only 3 out of 32 studies showed an improvement in body fat loss in diets low in dietary carbohydrates, while the vast majority showed a large body fat loss in low-fat diets.
These results were opposite to those predicted by the carbohydrate-insulin hypothesis, and refute any so-called metabolic advantage from replacing carbohydrates with fats. 
Carbohydrate-Insulin Hypothesis of No-Sugar Weight Loss Diet
For those who don’t know, the once proposed carbohydrate-insulin hypothesis predicted that a decrease in dietary carbohydrate levels would lead to a significant decrease in insulin levels, which would lead to the release of fat from adipocytes, and this would help:
- increase fat loss
- increase energy consumption at rest in the range of 400-600 kcal per day.
However, none of these effects, despite a recorded decrease in insulin (and glucose) levels as a result of replacing carbohydrates with fats, was observed in two relevant and very strict metabolic studies [5, 6]. One of which was actually conducted by the Nutrition Science Initiative (NuSI). It is noteworthy that this organization was specially created to finance and sponsor research aimed at demonstrating the effectiveness of low-carb diets. Honestly, they failed to demonstrate the effectiveness, but thanks for the honesty in the conclusions. 
Later, in 2020, under the leadership of the author of the two studies mentioned above – Kevin D. Hall, another study was conducted in which the two groups alternately adhered to a ketogenic low-carb diet (fats-75.8%, carbs-10%, protein-14, 2%) and low-fat high-carb (c-75.2%, f-10.3%, p-14.5%) for two weeks each.
At the same time, a low-fat diet showed higher levels of glucose and insulin, and a low-carb increase in the level of circulating ketones. Compared to the ketogenic diet, a low-fat diet led to a spontaneous decrease in energy consumption by an average of 689 kcal with an ad libitum diet (without limitation) consistently in all subjects, which contradicts the predictions of the carbohydrate-insulin model of obesity.
Despite a reduction in energy intake only in low-fat protocols, a ketogenic diet led to rapid weight loss during the first week, due to a decrease in muscle mass and water. A decrease in energy consumption in a low-fat diet led to a decrease in total body weight and fat mass, which was not accompanied by a change in appetite. Losses of total body weight over two weeks were the same for each of the diets.
The ketogenic diet increased the oxidation of fat by cells but also increased the deposition of dietary fat in adipocytes since their amount was high in the diet (fat from food is mostly deposited in fat cells under any conditions). A low-fat, high-carb diet reduced the oxidation of fat but also reduced the amount deposited (since there is little fat in the diet).
Between the two types of diets, the overall balance of fat (the difference between consumption and accumulation) was almost equal. The first “burns” more, but also accumulates more, the other “burns” less, but also accumulates less. Similar results were recorded in previous studies. Thus, the benefits of a ketogenic diet were only in controlling glucose and insulin levels, which may be important for people with metabolic diseases.
But changing insulin secretion to a greater or lesser extent does not have a significant effect on weight loss. Because insulin “horror stories” in relation to sugar, also, can not be truthful.
Is it worth counting the amount of sugar when losing weight?
Does the above mean that you can not bother with the amount of sugar in the ration on a diet aimed at losing weight? – No.
We must not forget that a ration is not only a certain calorie diet, as well as the number of proteins, fats, and carbohydrates, but also nutrition management tactics aimed at more or less comfortable maintenance of energy deficiency. The feeling of hunger and lack of satiation for many become an insurmountable obstacle to weight loss. Therefore, we must be able to fight them. And reducing sugar can be part of the tactics of such a fight.
For example, sweetened drinks cause a lesser sense of fullness, which often leads to their consumption in large quantities, and solid foods containing sugar very often have an increased energy density (for example, cookies, ice cream, chocolate), which means that it’s much easier to get excess energy when consuming such food than from another.
In addition, in conditions of limited food consumption, the amount of vital substances entering the body decreases vitamins, minerals, trace elements, dietary fiber, etc. Sugar is a refined source of carbohydrates. The more we introduce it into the diet, the more we are forced to exclude other carbohydrate sources, including with high nutritional value—for example, whole grains, legumes, fruits.
Everything is simple. Sugar consumption alone does not prevent weight loss. However, when it becomes too much, this will affect both the quality of power and the ability to control the level of energy consumption.
Keep moderation and avoid extremes, as in any other business.
No-Sugar Weight Loss Diet Sources
- Dietary sugars and body weight: systematic review and meta-analyses of randomised controlled trials and cohort studies. Lisa Te Morenga, Simonette Mallard, Jim Mann. BMJ 2013.
- Relevance of the Glycemic Index and Glycemic Load for Body Weight, Diabetes, and Cardiovascular Disease. Sonia Vega-López, Bernard J. Venn, and Joanne L. Slavin. Nutrients. 2018 Oct; 10(10): 1361. Published online 2018 Sep 22.
- Parks, EJ (2002) The relationship of the glycemic index to lipogenesis in humans. In Proceedings of the 6th (Millenium) Vahouny Conference, [Kritchevsky, D, editor]
- Obesity energetics: body weight regulation and the effects of diet compositionHall KD, Guo J. Gastroenterology 152: 1718–1727.e3, 2017.
- Calorie for calorie, dietary fat restriction results in more body fat loss than carbohydrate restriction in people with obesity Kevin D. Hall, Thomas Bemis, Robert Brychta, Kong Y. Chen, Amber Courville, Emma J. Crayner, Stephanie Goodwin, Juen Guo, Lilian Howard, Nicolas D. Knuth, Bernard V. Miller, Carla M. Prado, Mario Siervo, Monica C. Skarulis, Mary Walter, Peter J. Walter, and Laura Yannai1.Cell Metab. Author manuscript; available in PMC 2016 Sep 1.
- Energy expenditure and body composition changes after an isocaloric ketogenic diet in overweight and obese men. Hall KD, Chen KY, Guo J, Lam YY, Leibel RL, Mayer LE, Reitman ML, Rosenbaum M, Smith SR, Walsh BT, Ravussin E. Am J Clin Nutr. 2016 Aug;104(2):324-33.
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